Science.gov

Sample records for accurate source location

  1. Accurate source location from waves scattered by surface topography

    NASA Astrophysics Data System (ADS)

    Wang, Nian; Shen, Yang; Flinders, Ashton; Zhang, Wei

    2016-06-01

    Accurate source locations of earthquakes and other seismic events are fundamental in seismology. The location accuracy is limited by several factors, including velocity models, which are often poorly known. In contrast, surface topography, the largest velocity contrast in the Earth, is often precisely mapped at the seismic wavelength (>100 m). In this study, we explore the use of P coda waves generated by scattering at surface topography to obtain high-resolution locations of near-surface seismic events. The Pacific Northwest region is chosen as an example to provide realistic topography. A grid search algorithm is combined with the 3-D strain Green's tensor database to improve search efficiency as well as the quality of hypocenter solutions. The strain Green's tensor is calculated using a 3-D collocated-grid finite difference method on curvilinear grids. Solutions in the search volume are obtained based on the least squares misfit between the "observed" and predicted P and P coda waves. The 95% confidence interval of the solution is provided as an a posteriori error estimation. For shallow events tested in the study, scattering is mainly due to topography in comparison with stochastic lateral velocity heterogeneity. The incorporation of P coda significantly improves solution accuracy and reduces solution uncertainty. The solution remains robust with wide ranges of random noises in data, unmodeled random velocity heterogeneities, and uncertainties in moment tensors. The method can be extended to locate pairs of sources in close proximity by differential waveforms using source-receiver reciprocity, further reducing errors caused by unmodeled velocity structures.

  2. Accurate source location from P waves scattered by surface topography

    NASA Astrophysics Data System (ADS)

    Wang, N.; Shen, Y.

    2015-12-01

    Accurate source locations of earthquakes and other seismic events are fundamental in seismology. The location accuracy is limited by several factors, including velocity models, which are often poorly known. In contrast, surface topography, the largest velocity contrast in the Earth, is often precisely mapped at the seismic wavelength (> 100 m). In this study, we explore the use of P-coda waves generated by scattering at surface topography to obtain high-resolution locations of near-surface seismic events. The Pacific Northwest region is chosen as an example. The grid search method is combined with the 3D strain Green's tensor database type method to improve the search efficiency as well as the quality of hypocenter solution. The strain Green's tensor is calculated by the 3D collocated-grid finite difference method on curvilinear grids. Solutions in the search volume are then obtained based on the least-square misfit between the 'observed' and predicted P and P-coda waves. A 95% confidence interval of the solution is also provided as a posterior error estimation. We find that the scattered waves are mainly due to topography in comparison with random velocity heterogeneity characterized by the von Kάrmάn-type power spectral density function. When only P wave data is used, the 'best' solution is offset from the real source location mostly in the vertical direction. The incorporation of P coda significantly improves solution accuracy and reduces its uncertainty. The solution remains robust with a range of random noises in data, un-modeled random velocity heterogeneities, and uncertainties in moment tensors that we tested.

  3. Alignment of leading-edge and peak-picking time of arrival methods to obtain accurate source locations

    SciTech Connect

    Roussel-Dupre, R.; Symbalisty, E.; Fox, C.; and Vanderlinde, O.

    2009-08-01

    The location of a radiating source can be determined by time-tagging the arrival of the radiated signal at a network of spatially distributed sensors. The accuracy of this approach depends strongly on the particular time-tagging algorithm employed at each of the sensors. If different techniques are used across the network, then the time tags must be referenced to a common fiducial for maximum location accuracy. In this report we derive the time corrections needed to temporally align leading-edge, time-tagging techniques with peak-picking algorithms. We focus on broadband radio frequency (RF) sources, an ionospheric propagation channel, and narrowband receivers, but the final results can be generalized to apply to any source, propagation environment, and sensor. Our analytic results are checked against numerical simulations for a number of representative cases and agree with the specific leading-edge algorithm studied independently by Kim and Eng (1995) and Pongratz (2005 and 2007).

  4. Acoustic emission source location

    NASA Astrophysics Data System (ADS)

    Promboon, Yajai

    The objective of the research program was development of reliable source location techniques. The study comprised two phases. First, the research focused on development of source location methods for homogeneous plates. The specimens used in the program were steel railroad tank cars. Source location methods were developed and demonstrated for empty and water filled tanks. The second phase of the research was an exploratory study of source location method for fiber reinforced composites. Theoretical analysis and experimental measurement of wave propagation were carried out. This data provided the basis for development of a method using the intersection of the group velocity curves for the first three wave propagation modes. Simplex optimization was used to calculate the location of the source. Additional source location methods have been investigated and critically examined. Emphasis has been placed on evaluating different methods for determining the time of arrival of a wave. The behavior of wave in a water filled tank was studied and source location methods suitable for use in this situation have been examined through experiment and theory. Particular attention is paid to the problem caused by leaky Lamb waves. A preliminary study into the use of neural networks for source location in fiber reinforced composites was included in the research program. A preliminary neural network model and the results from training and testing data are reported.

  5. Accurate tremor locations from coherent S and P waves

    NASA Astrophysics Data System (ADS)

    Armbruster, John G.; Kim, Won-Young; Rubin, Allan M.

    2014-06-01

    Nonvolcanic tremor is an important component of the slow slip processes which load faults from below, but accurately locating tremor has proven difficult because tremor rarely contains clear P or S wave arrivals. Here we report the observation of coherence in the shear and compressional waves of tremor at widely separated stations which allows us to detect and accurately locate tremor events. An event detector using data from two stations sees the onset of tremor activity in the Cascadia tremor episodes of February 2003, July 2004, and September 2005 and confirms the previously reported south to north migration of the tremor. Event detectors using data from three and four stations give Sand P arrival times of high accuracy. The hypocenters of the tremor events fall at depths of ˜30 to ˜40 km and define a narrow plane dipping at a shallow angle to the northeast, consistent with the subducting plate interface. The S wave polarizations and P wave first motions define a source mechanism in agreement with the northeast convergence seen in geodetic observations of slow slip. Tens of thousands of locations determined by constraining the events to the plate interface show tremor sources highly clustered in space with a strongly similar pattern of sources in the three episodes examined. The deeper sources generate tremor in minor episodes as well. The extent to which the narrow bands of tremor sources overlap between the three major episodes suggests relative epicentral location errors as small as 1-2 km.

  6. Accurate Tremor Locations in Japan from Coherent S-Waves

    NASA Astrophysics Data System (ADS)

    Armbruster, J. G.

    2014-12-01

    The tremor detectors developed for accurately locating tectonic tremor in Cascadia [Armbruster et al., JGR 2014] have been applied to data from the HINET seismic network in Japan. The best results were obtained in the Tokai region with stations ASU, ASH and TYE having relatively close spacing (11-18 km). 330 days with active tremor, 2004-2014, near these stations were found on the daily epicentral distributions of tremor on the HINET web site. The detector sees numbers of detections per day comparable to minor tremor episodes in Cascadia. Major tremor episodes in Cascadia are associated with geodetic signals stronger than those seen in Japan. If the tremor is located by constraining it to the plate interface, a pattern of persistent sources is seen, with some intense sources. This is similar to what was seen in Cascadia. In southwest Shikoku 139 days with tremor were identified. Stations UWA, OOZ and IKT see tremor with persistent patterns and strong sources but with approximately one fifth as many detections per day on active days, compared to ASU-ASH-TYE. The web site tremor distributions show activity here as strong as in Tokai. We believe the lesser number of detections in Shikoku is primarily the result of wider station spacing, 19-30 km, than in Tokai, although there may be other factors. Yabe and Ide [EPS 2013] detect and locate tremor in Kyushu on July 17-18 2005 and December 4-6 2008. A detector with stations NRA, SUK and KTM, station spacing 21-22 km, sees tremor which resembles minor episodes in Cascadia. The relative arrival times are consistent with their locations. We conclude that the methods developed in Cascadia will work in Japan but the typical spacing of HINET stations, ~20 km, is greater than the optimum distance found in analysis of data from Cascadia, 8 to 15 km.

  7. Nonexposure accurate location K-anonymity algorithm in LBS.

    PubMed

    Jia, Jinying; Zhang, Fengli

    2014-01-01

    This paper tackles location privacy protection in current location-based services (LBS) where mobile users have to report their exact location information to an LBS provider in order to obtain their desired services. Location cloaking has been proposed and well studied to protect user privacy. It blurs the user's accurate coordinate and replaces it with a well-shaped cloaked region. However, to obtain such an anonymous spatial region (ASR), nearly all existent cloaking algorithms require knowing the accurate locations of all users. Therefore, location cloaking without exposing the user's accurate location to any party is urgently needed. In this paper, we present such two nonexposure accurate location cloaking algorithms. They are designed for K-anonymity, and cloaking is performed based on the identifications (IDs) of the grid areas which were reported by all the users, instead of directly on their accurate coordinates. Experimental results show that our algorithms are more secure than the existent cloaking algorithms, need not have all the users reporting their locations all the time, and can generate smaller ASR. PMID:24605060

  8. Nonexposure Accurate Location K-Anonymity Algorithm in LBS

    PubMed Central

    2014-01-01

    This paper tackles location privacy protection in current location-based services (LBS) where mobile users have to report their exact location information to an LBS provider in order to obtain their desired services. Location cloaking has been proposed and well studied to protect user privacy. It blurs the user's accurate coordinate and replaces it with a well-shaped cloaked region. However, to obtain such an anonymous spatial region (ASR), nearly all existent cloaking algorithms require knowing the accurate locations of all users. Therefore, location cloaking without exposing the user's accurate location to any party is urgently needed. In this paper, we present such two nonexposure accurate location cloaking algorithms. They are designed for K-anonymity, and cloaking is performed based on the identifications (IDs) of the grid areas which were reported by all the users, instead of directly on their accurate coordinates. Experimental results show that our algorithms are more secure than the existent cloaking algorithms, need not have all the users reporting their locations all the time, and can generate smaller ASR. PMID:24605060

  9. Source Identification and Location Techniques

    NASA Technical Reports Server (NTRS)

    Weir, Donald; Bridges, James; Agboola, Femi; Dougherty, Robert

    2001-01-01

    Mr. Weir presented source location results obtained from an engine test as part of the Engine Validation of Noise Reduction Concepts program. Two types of microphone arrays were used in this program to determine the jet noise source distribution for the exhaust from a 4.3 bypass ratio turbofan engine. One was a linear array of 16 microphones located on a 25 ft. sideline and the other was a 103 microphone 3-D "cage" array in the near field of the jet. Data were obtained from a baseline nozzle and from numerous nozzle configuration using chevrons and/or tabs to reduce the jet noise. Mr. Weir presented data from two configurations: the baseline nozzle and a nozzle configuration with chevrons on both the core and bypass nozzles. This chevron configuration had achieved a jet noise reduction of 4 EPNdB in small scale tests conducted at the Glenn Research Center. IR imaging showed that the chevrons produced significant improvements in mixing and greatly reduced the length of the jet potential core. Comparison of source location data from the 1-D phased array showed a shift of the noise sources towards the nozzle and clear reductions of the sources due to the noise reduction devices. Data from the 3-D array showed a single source at a frequency of 125 Hz. located several diameters downstream from the nozzle exit. At 250 and 400 Hz., multiple sources, periodically spaced, appeared to exist downstream of the nozzle. The trend of source location moving toward the nozzle exit with increasing frequency was also observed. The 3-D array data also showed a reduction in source strength with the addition of chevrons. The overall trend of source location with frequency was compared for the two arrays and with classical experience. Similar trends were observed. Although overall trends with frequency and addition of suppression devices were consistent between the data from the 1-D and the 3-D arrays, a comparison of the details of the inferred source locations did show differences. A

  10. Accurate eye center location through invariant isocentric patterns.

    PubMed

    Valenti, Roberto; Gevers, Theo

    2012-09-01

    Locating the center of the eyes allows for valuable information to be captured and used in a wide range of applications. Accurate eye center location can be determined using commercial eye-gaze trackers, but additional constraints and expensive hardware make these existing solutions unattractive and impossible to use on standard (i.e., visible wavelength), low-resolution images of eyes. Systems based solely on appearance are proposed in the literature, but their accuracy does not allow us to accurately locate and distinguish eye centers movements in these low-resolution settings. Our aim is to bridge this gap by locating the center of the eye within the area of the pupil on low-resolution images taken from a webcam or a similar device. The proposed method makes use of isophote properties to gain invariance to linear lighting changes (contrast and brightness), to achieve in-plane rotational invariance, and to keep low-computational costs. To further gain scale invariance, the approach is applied to a scale space pyramid. In this paper, we extensively test our approach for its robustness to changes in illumination, head pose, scale, occlusion, and eye rotation. We demonstrate that our system can achieve a significant improvement in accuracy over state-of-the-art techniques for eye center location in standard low-resolution imagery. PMID:22813958

  11. Point Source Location Sensitivity Analysis

    NASA Astrophysics Data System (ADS)

    Cox, J. Allen

    1986-11-01

    This paper presents the results of an analysis of point source location accuracy and sensitivity as a function of focal plane geometry, optical blur spot, and location algorithm. Five specific blur spots are treated: gaussian, diffraction-limited circular aperture with and without central obscuration (obscured and clear bessinc, respectively), diffraction-limited rectangular aperture, and a pill box distribution. For each blur spot, location accuracies are calculated for square, rectangular, and hexagonal detector shapes of equal area. The rectangular detectors are arranged on a hexagonal lattice. The two location algorithms consist of standard and generalized centroid techniques. Hexagonal detector arrays are shown to give the best performance under a wide range of conditions.

  12. Accurate shear measurement with faint sources

    SciTech Connect

    Zhang, Jun; Foucaud, Sebastien; Luo, Wentao E-mail: walt@shao.ac.cn

    2015-01-01

    For cosmic shear to become an accurate cosmological probe, systematic errors in the shear measurement method must be unambiguously identified and corrected for. Previous work of this series has demonstrated that cosmic shears can be measured accurately in Fourier space in the presence of background noise and finite pixel size, without assumptions on the morphologies of galaxy and PSF. The remaining major source of error is source Poisson noise, due to the finiteness of source photon number. This problem is particularly important for faint galaxies in space-based weak lensing measurements, and for ground-based images of short exposure times. In this work, we propose a simple and rigorous way of removing the shear bias from the source Poisson noise. Our noise treatment can be generalized for images made of multiple exposures through MultiDrizzle. This is demonstrated with the SDSS and COSMOS/ACS data. With a large ensemble of mock galaxy images of unrestricted morphologies, we show that our shear measurement method can achieve sub-percent level accuracy even for images of signal-to-noise ratio less than 5 in general, making it the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys.

  13. Hydrogen atoms can be located accurately and precisely by x-ray crystallography.

    PubMed

    Woińska, Magdalena; Grabowsky, Simon; Dominiak, Paulina M; Woźniak, Krzysztof; Jayatilaka, Dylan

    2016-05-01

    Precise and accurate structural information on hydrogen atoms is crucial to the study of energies of interactions important for crystal engineering, materials science, medicine, and pharmacy, and to the estimation of physical and chemical properties in solids. However, hydrogen atoms only scatter x-radiation weakly, so x-rays have not been used routinely to locate them accurately. Textbooks and teaching classes still emphasize that hydrogen atoms cannot be located with x-rays close to heavy elements; instead, neutron diffraction is needed. We show that, contrary to widespread expectation, hydrogen atoms can be located very accurately using x-ray diffraction, yielding bond lengths involving hydrogen atoms (A-H) that are in agreement with results from neutron diffraction mostly within a single standard deviation. The precision of the determination is also comparable between x-ray and neutron diffraction results. This has been achieved at resolutions as low as 0.8 Å using Hirshfeld atom refinement (HAR). We have applied HAR to 81 crystal structures of organic molecules and compared the A-H bond lengths with those from neutron measurements for A-H bonds sorted into bonds of the same class. We further show in a selection of inorganic compounds that hydrogen atoms can be located in bridging positions and close to heavy transition metals accurately and precisely. We anticipate that, in the future, conventional x-radiation sources at in-house diffractometers can be used routinely for locating hydrogen atoms in small molecules accurately instead of large-scale facilities such as spallation sources or nuclear reactors. PMID:27386545

  14. Hydrogen atoms can be located accurately and precisely by x-ray crystallography

    PubMed Central

    Woińska, Magdalena; Grabowsky, Simon; Dominiak, Paulina M.; Woźniak, Krzysztof; Jayatilaka, Dylan

    2016-01-01

    Precise and accurate structural information on hydrogen atoms is crucial to the study of energies of interactions important for crystal engineering, materials science, medicine, and pharmacy, and to the estimation of physical and chemical properties in solids. However, hydrogen atoms only scatter x-radiation weakly, so x-rays have not been used routinely to locate them accurately. Textbooks and teaching classes still emphasize that hydrogen atoms cannot be located with x-rays close to heavy elements; instead, neutron diffraction is needed. We show that, contrary to widespread expectation, hydrogen atoms can be located very accurately using x-ray diffraction, yielding bond lengths involving hydrogen atoms (A–H) that are in agreement with results from neutron diffraction mostly within a single standard deviation. The precision of the determination is also comparable between x-ray and neutron diffraction results. This has been achieved at resolutions as low as 0.8 Å using Hirshfeld atom refinement (HAR). We have applied HAR to 81 crystal structures of organic molecules and compared the A–H bond lengths with those from neutron measurements for A–H bonds sorted into bonds of the same class. We further show in a selection of inorganic compounds that hydrogen atoms can be located in bridging positions and close to heavy transition metals accurately and precisely. We anticipate that, in the future, conventional x-radiation sources at in-house diffractometers can be used routinely for locating hydrogen atoms in small molecules accurately instead of large-scale facilities such as spallation sources or nuclear reactors. PMID:27386545

  15. Codes for sound-source location in nontonotopic auditory cortex.

    PubMed

    Middlebrooks, J C; Xu, L; Eddins, A C; Green, D M

    1998-08-01

    We evaluated two hypothetical codes for sound-source location in the auditory cortex. The topographical code assumed that single neurons are selective for particular locations and that sound-source locations are coded by the cortical location of small populations of maximally activated neurons. The distributed code assumed that the responses of individual neurons can carry information about locations throughout 360 degrees of azimuth and that accurate sound localization derives from information that is distributed across large populations of such panoramic neurons. We recorded from single units in the anterior ectosylvian sulcus area (area AES) and in area A2 of alpha-chloralose-anesthetized cats. Results obtained in the two areas were essentially equivalent. Noise bursts were presented from loudspeakers spaced in 20 degrees intervals of azimuth throughout 360 degrees of the horizontal plane. Spike counts of the majority of units were modulated >50% by changes in sound-source azimuth. Nevertheless, sound-source locations that produced greater than half-maximal spike counts often spanned >180 degrees of azimuth. The spatial selectivity of units tended to broaden and, often, to shift in azimuth as sound pressure levels (SPLs) were increased to a moderate level. We sometimes saw systematic changes in spatial tuning along segments of electrode tracks as long as 1.5 mm but such progressions were not evident at higher sound levels. Moderate-level sounds presented anywhere in the contralateral hemifield produced greater than half-maximal activation of nearly all units. These results are not consistent with the hypothesis of a topographic code. We used an artificial-neural-network algorithm to recognize spike patterns and, thereby, infer the locations of sound sources. Network input consisted of spike density functions formed by averages of responses to eight stimulus repetitions. Information carried in the responses of single units permitted reasonable estimates of sound-source

  16. Locating Microseism Sources in Offshore Southern California

    NASA Astrophysics Data System (ADS)

    Tian, X.; Clayton, R. W.

    2007-12-01

    We use the broadband stations from the S. California network to locate the apparent origin of secondary microseisms energy (5-8 Hz band). The procedure is to grid the offshore region and using each grid point as the source point, predict the response of a Rayleigh wave at each station. These predicted waveforms are then correlated with the data over a time window that is typically a 1/2 hour in length and composited at the grid point. The length of the time window controls a tradeoff between the spatial-temporal resolution of the sources and the robustness on the image. The procedure is valid for multiple sources. This results show that during periods of high microseism activity the sources are distinct at several locations in a region approximately 50-100 km offshore. For an 11/09/2002 Southern Ocean storm, for example, two zones parallel to each other and perpendicular to the coast are imaged.

  17. Locating POPs Sources with Tree Bark.

    PubMed

    Peverly, Angela A; Salamova, Amina; Hites, Ronald A

    2015-12-01

    Locating sources of persistent organic pollutants (POPs) to the atmosphere can sometimes be difficult. We suggest that tree bark makes an excellent passive atmospheric sampler and that spatial analysis of tree bark POPs concentrations can often pinpoint their sources. This is an effective strategy because tree bark is lipophilic and readily adsorbs and collects POPs from the atmosphere. As such, tree bark is an ideal sampler to find POPs sources globally, regionally, or locally. This article summarizes some work on this subject with an emphasis on kriged maps and a simple power-law model, both of which have been used to locate sources. Three of the four examples led directly to the pollutant's manufacturing plant. PMID:25629888

  18. Continuous wavelet transform analysis and modal location analysis acoustic emission source location for nuclear piping crack growth monitoring

    SciTech Connect

    Mohd, Shukri; Holford, Karen M.; Pullin, Rhys

    2014-02-12

    Source location is an important feature of acoustic emission (AE) damage monitoring in nuclear piping. The ability to accurately locate sources can assist in source characterisation and early warning of failure. This paper describe the development of a novelAE source location technique termed 'Wavelet Transform analysis and Modal Location (WTML)' based on Lamb wave theory and time-frequency analysis that can be used for global monitoring of plate like steel structures. Source location was performed on a steel pipe of 1500 mm long and 220 mm outer diameter with nominal thickness of 5 mm under a planar location test setup using H-N sources. The accuracy of the new technique was compared with other AE source location methods such as the time of arrival (TOA) techniqueand DeltaTlocation. Theresults of the study show that the WTML method produces more accurate location resultscompared with TOA and triple point filtering location methods. The accuracy of the WTML approach is comparable with the deltaT location method but requires no initial acoustic calibration of the structure.

  19. Locating industrial VOC sources with aircraft observations.

    PubMed

    Toscano, P; Gioli, B; Dugheri, S; Salvini, A; Matese, A; Bonacchi, A; Zaldei, A; Cupelli, V; Miglietta, F

    2011-05-01

    Observation and characterization of environmental pollution, focussing on Volatile Organic Compounds (VOCs), in a high-risk industrial area, are particularly important in order to provide indications on a safe level of exposure, indicate eventual priorities and advise on policy interventions. The aim of this study is to use the Solid Phase Micro Extraction (SPME) method to measure VOCs, directly coupled with atmospheric measurements taken on a small aircraft environmental platform, to evaluate and locate the presence of VOC emission sources in the Marghera industrial area. Lab analysis of collected SPME fibres and subsequent analysis of mass spectrum and chromatograms in Scan Mode allowed the detection of a wide range of VOCs. The combination of this information during the monitoring campaign allowed a model (Gaussian Plume) to be implemented that estimates the localization of emission sources on the ground. PMID:21376441

  20. An information-theoretic approach to microseismic source location

    NASA Astrophysics Data System (ADS)

    Prange, Michael D.; Bose, Sandip; Kodio, Ousmane; Djikpesse, Hugues A.

    2015-04-01

    There has been extensive work on seismic source localization, going as far back as Geiger's 1912 paper, that is based on least-squares fitting of arrival times. The primary advantage of time-based methods over waveform-based methods (e.g. reverse-time migration and beam forming) is that simulated arrival times are considerably more reliable than simulated waveforms, especially in the context of an uncertain velocity model, thereby yielding more reliable estimates of source location. However, time-based methods are bedeviled by the unsolved challenges of accurate time picking and labelling of the seismic phases in the waveforms for each event. Drawing from Woodward's canonical 1953 text on the application of information theory to radar applications, we show that time-based methods can be applied directly to waveform data, thus capturing the advantages of time-based methods without being impacted by the aforementioned hindrances. We extend Woodward's approach to include an unknown distortion on wavelet amplitude and phase, showing that the related marginalization integrals can be analytically evaluated. We also provide extensions for correlation-based location methods such as relative localization and the S-P method. We demonstrate this approach through applications to microseismic event location, presenting formulations and results for both absolute and relative localization approaches, with receiver arrays either in a borehole or on the surface. By properly quantifying uncertainty in our location estimates, our formulations provide an objective measure for ranking the accuracy of microseismic source location methodologies.

  1. Inversely tracking indoor airborne particles to locate their release sources

    NASA Astrophysics Data System (ADS)

    Zhang, Tengfei (Tim); Li, Hongzhu; Wang, Shugang

    2012-08-01

    Airborne particles can have numerous adverse effects on human health. Knowing the release locations of airborne particulate sources is helpful in minimizing pollutant exposure. This paper describes a proposal to locate indoor particulate sources by two inverse models: the quasi-reversibility (QR) model and the zone prescription of contaminant sources with the Lagrangian-reversibility (LR) model. The QR model reverses the time marching direction of the Eulerian governing equation and replaces the second-order diffusion term with a fourth-order stabilization term. The zone prescription LR model traces individual particulate motion in a Lagrangian reference frame after reversing the flow field. The particle trajectories are solved backward to the initial release once the conservative forces acting on particles are reversed. The tracked particles are proposed to be placed at the zone boundary of the largest concentration contour within the domain at a given time, which is provided as the initially known information. By connecting all particles at t = 0, a zone is formed that can prescribe the actual contaminant source. This study finds that both models can accurately locate particulate sources released instantaneously at a spot. The QR model performs slightly better than the LR model but is much more computationally demanding.

  2. Development of an accurate transmission line fault locator using the global positioning system satellites

    NASA Technical Reports Server (NTRS)

    Lee, Harry

    1994-01-01

    A highly accurate transmission line fault locator based on the traveling-wave principle was developed and successfully operated within B.C. Hydro. A transmission line fault produces a fast-risetime traveling wave at the fault point which propagates along the transmission line. This fault locator system consists of traveling wave detectors located at key substations which detect and time tag the leading edge of the fault-generated traveling wave as if passes through. A master station gathers the time-tagged information from the remote detectors and determines the location of the fault. Precise time is a key element to the success of this system. This fault locator system derives its timing from the Global Positioning System (GPS) satellites. System tests confirmed the accuracy of locating faults to within the design objective of +/-300 meters.

  3. Accurate radio and optical positions for southern radio sources

    NASA Technical Reports Server (NTRS)

    Harvey, Bruce R.; Jauncey, David L.; White, Graeme L.; Nothnagel, Axel; Nicolson, George D.; Reynolds, John E.; Morabito, David D.; Bartel, Norbert

    1992-01-01

    Accurate radio positions with a precision of about 0.01 arcsec are reported for eight compact extragalactic radio sources south of -45-deg declination. The radio positions were determined using VLBI at 8.4 GHz on the 9589 km Tidbinbilla (Australia) to Hartebeesthoek (South Africa) baseline. The sources were selected from the Parkes Catalogue to be strong, flat-spectrum radio sources with bright optical QSO counterparts. Optical positions of the QSOs were also measured from the ESO B Sky Survey plates with respect to stars from the Perth 70 Catalogue, to an accuracy of about 0.19 arcsec rms. These radio and optical positions are as precise as any presently available in the far southern sky. A comparison of the radio and optical positions confirms the estimated optical position errors and shows that there is overall agreement at the 0.1-arcsec level between the radio and Perth 70 optical reference frames in the far south.

  4. Fast, accurate, robust and Open Source Brain Extraction Tool (OSBET)

    NASA Astrophysics Data System (ADS)

    Namias, R.; Donnelly Kehoe, P.; D'Amato, J. P.; Nagel, J.

    2015-12-01

    The removal of non-brain regions in neuroimaging is a critical task to perform a favorable preprocessing. The skull-stripping depends on different factors including the noise level in the image, the anatomy of the subject being scanned and the acquisition sequence. For these and other reasons, an ideal brain extraction method should be fast, accurate, user friendly, open-source and knowledge based (to allow for the interaction with the algorithm in case the expected outcome is not being obtained), producing stable results and making it possible to automate the process for large datasets. There are already a large number of validated tools to perform this task but none of them meets the desired characteristics. In this paper we introduced an open source brain extraction tool (OSBET), composed of four steps using simple well-known operations such as: optimal thresholding, binary morphology, labeling and geometrical analysis that aims to assemble all the desired features. We present an experiment comparing OSBET with other six state-of-the-art techniques against a publicly available dataset consisting of 40 T1-weighted 3D scans and their corresponding manually segmented images. OSBET gave both: a short duration with an excellent accuracy, getting the best Dice Coefficient metric. Further validation should be performed, for instance, in unhealthy population, to generalize its usage for clinical purposes.

  5. The application of Shuffled Frog Leaping Algorithm to Wavelet Neural Networks for acoustic emission source location

    NASA Astrophysics Data System (ADS)

    Cheng, Xinmin; Zhang, Xiaodan; Zhao, Li; Deng, Aideng; Bao, Yongqiang; Liu, Yong; Jiang, Yunliang

    2014-04-01

    When using acoustic emission to locate the friction fault source of rotating machinery, the effects of strong noise and waveform distortion make accurate locating difficult. Applying neural network for acoustic emission source location could be helpful. In the BP Wavelet Neural Network, BP is a local search algorithm, which falls into local minimum easily. The probability of successful search is low. We used Shuffled Frog Leaping Algorithm (SFLA) to optimize the parameters of the Wavelet Neural Network, and the optimized Wavelet Neural Network to locate the source. After having performed the experiments of friction acoustic emission's source location on the rotor friction test machine, the results show that the calculation of SFLA is simple and effective, and that locating is accurate with proper structure of the network and input parameters.

  6. Accurate Damage Location in Complex Composite Structures and Industrial Environments using Acoustic Emission

    NASA Astrophysics Data System (ADS)

    Eaton, M.; Pearson, M.; Lee, W.; Pullin, R.

    2015-07-01

    The ability to accurately locate damage in any given structure is a highly desirable attribute for an effective structural health monitoring system and could help to reduce operating costs and improve safety. This becomes a far greater challenge in complex geometries and materials, such as modern composite airframes. The poor translation of promising laboratory based SHM demonstrators to industrial environments forms a barrier to commercial up take of technology. The acoustic emission (AE) technique is a passive NDT method that detects elastic stress waves released by the growth of damage. It offers very sensitive damage detection, using a sparse array of sensors to detect and globally locate damage within a structure. However its application to complex structures commonly yields poor accuracy due to anisotropic wave propagation and the interruption of wave propagation by structural features such as holes and thickness changes. This work adopts an empirical mapping technique for AE location, known as Delta T Mapping, which uses experimental training data to account for such structural complexities. The technique is applied to a complex geometry composite aerospace structure undergoing certification testing. The component consists of a carbon fibre composite tube with varying wall thickness and multiple holes, that was loaded under bending. The damage location was validated using X-ray CT scanning and the Delta T Mapping technique was shown to improve location accuracy when compared with commercial algorithms. The onset and progression of damage were monitored throughout the test and used to inform future design iterations.

  7. Distributed fiber sensing system with wide frequency response and accurate location

    NASA Astrophysics Data System (ADS)

    Shi, Yi; Feng, Hao; Zeng, Zhoumo

    2016-02-01

    A distributed fiber sensing system merging Mach-Zehnder interferometer and phase-sensitive optical time domain reflectometer (Φ-OTDR) is demonstrated for vibration measurement, which requires wide frequency response and accurate location. Two narrow line-width lasers with delicately different wavelengths are used to constitute the interferometer and reflectometer respectively. A narrow band Fiber Bragg Grating is responsible for separating the two wavelengths. In addition, heterodyne detection is applied to maintain the signal to noise rate of the locating signal. Experiment results show that the novel system has a wide frequency from 1 Hz to 50 MHz, limited by the sample frequency of data acquisition card, and a spatial resolution of 20 m, according to 200 ns pulse width, along 2.5 km fiber link.

  8. Accurate Vehicle Location System Using RFID, an Internet of Things Approach

    PubMed Central

    Prinsloo, Jaco; Malekian, Reza

    2016-01-01

    Modern infrastructure, such as dense urban areas and underground tunnels, can effectively block all GPS signals, which implies that effective position triangulation will not be achieved. The main problem that is addressed in this project is the design and implementation of an accurate vehicle location system using radio-frequency identification (RFID) technology in combination with GPS and the Global system for Mobile communication (GSM) technology, in order to provide a solution to the limitation discussed above. In essence, autonomous vehicle tracking will be facilitated with the use of RFID technology where GPS signals are non-existent. The design of the system and the results are reflected in this paper. An extensive literature study was done on the field known as the Internet of Things, as well as various topics that covered the integration of independent technology in order to address a specific challenge. The proposed system is then designed and implemented. An RFID transponder was successfully designed and a read range of approximately 31 cm was obtained in the low frequency communication range (125 kHz to 134 kHz). The proposed system was designed, implemented, and field tested and it was found that a vehicle could be accurately located and tracked. It is also found that the antenna size of both the RFID reader unit and RFID transponder plays a critical role in the maximum communication range that can be achieved. PMID:27271638

  9. Accurate Vehicle Location System Using RFID, an Internet of Things Approach.

    PubMed

    Prinsloo, Jaco; Malekian, Reza

    2016-01-01

    Modern infrastructure, such as dense urban areas and underground tunnels, can effectively block all GPS signals, which implies that effective position triangulation will not be achieved. The main problem that is addressed in this project is the design and implementation of an accurate vehicle location system using radio-frequency identification (RFID) technology in combination with GPS and the Global system for Mobile communication (GSM) technology, in order to provide a solution to the limitation discussed above. In essence, autonomous vehicle tracking will be facilitated with the use of RFID technology where GPS signals are non-existent. The design of the system and the results are reflected in this paper. An extensive literature study was done on the field known as the Internet of Things, as well as various topics that covered the integration of independent technology in order to address a specific challenge. The proposed system is then designed and implemented. An RFID transponder was successfully designed and a read range of approximately 31 cm was obtained in the low frequency communication range (125 kHz to 134 kHz). The proposed system was designed, implemented, and field tested and it was found that a vehicle could be accurately located and tracked. It is also found that the antenna size of both the RFID reader unit and RFID transponder plays a critical role in the maximum communication range that can be achieved. PMID:27271638

  10. Accelerated food source location in aging Drosophila.

    PubMed

    Egenriether, Sada M; Chow, Eileen S; Krauth, Nathalie; Giebultowicz, Jadwiga M

    2015-10-01

    Adequate energy stores are essential for survival, and sophisticated neuroendocrine mechanisms evolved to stimulate foraging in response to nutrient deprivation. Food search behavior is usually investigated in young animals, and it is not known how aging alters this behavior. To address this question in Drosophila melanogaster, we compared the ability to locate food by olfaction in young and old flies using a food-filled trap. As aging is associated with a decline in motor functions, learning, and memory, we expected that aged flies would take longer to enter the food trap than their young counterparts. Surprisingly, old flies located food with significantly shorter latency than young ones. Robust food search behavior was associated with significantly lower fat reserves and lower starvation resistance in old flies. Food-finding latency (FFL) was shortened in young wild-type flies that were starved until their fat was depleted but also in heterozygous chico mutants with reduced insulin receptor activity and higher fat deposits. Conversely, food trap entry was delayed in old flies with increased insulin signaling. Our results suggest that the difference in FFL between young and old flies is linked to age-dependent differences in metabolic status and may be mediated by reduced insulin signaling. PMID:26102220

  11. Accurate prediction of V1 location from cortical folds in a surface coordinate system

    PubMed Central

    Hinds, Oliver P.; Rajendran, Niranjini; Polimeni, Jonathan R.; Augustinack, Jean C.; Wiggins, Graham; Wald, Lawrence L.; Rosas, H. Diana; Potthast, Andreas; Schwartz, Eric L.; Fischl, Bruce

    2008-01-01

    Previous studies demonstrated substantial variability of the location of primary visual cortex (V1) in stereotaxic coordinates when linear volume-based registration is used to match volumetric image intensities (Amunts et al., 2000). However, other qualitative reports of V1 location (Smith, 1904; Stensaas et al., 1974; Rademacher et al., 1993) suggested a consistent relationship between V1 and the surrounding cortical folds. Here, the relationship between folds and the location of V1 is quantified using surface-based analysis to generate a probabilistic atlas of human V1. High-resolution (about 200 μm) magnetic resonance imaging (MRI) at 7 T of ex vivo human cerebral hemispheres allowed identification of the full area via the stria of Gennari: a myeloarchitectonic feature specific to V1. Separate, whole-brain scans were acquired using MRI at 1.5 T to allow segmentation and mesh reconstruction of the cortical gray matter. For each individual, V1 was manually identified in the high-resolution volume and projected onto the cortical surface. Surface-based intersubject registration (Fischl et al., 1999b) was performed to align the primary cortical folds of individual hemispheres to those of a reference template representing the average folding pattern. An atlas of V1 location was constructed by computing the probability of V1 inclusion for each cortical location in the template space. This probabilistic atlas of V1 exhibits low prediction error compared to previous V1 probabilistic atlases built in volumetric coordinates. The increased predictability observed under surface-based registration suggests that the location of V1 is more accurately predicted by the cortical folds than by the shape of the brain embedded in the volume of the skull. In addition, the high quality of this atlas provides direct evidence that surface-based intersubject registration methods are superior to volume-based methods at superimposing functional areas of cortex, and therefore are better

  12. Accurate modeling and inversion of electrical resistivity data in the presence of metallic infrastructure with known location and dimension

    SciTech Connect

    Johnson, Timothy C.; Wellman, Dawn M.

    2015-06-26

    Electrical resistivity tomography (ERT) has been widely used in environmental applications to study processes associated with subsurface contaminants and contaminant remediation. Anthropogenic alterations in subsurface electrical conductivity associated with contamination often originate from highly industrialized areas with significant amounts of buried metallic infrastructure. The deleterious influence of such infrastructure on imaging results generally limits the utility of ERT where it might otherwise prove useful for subsurface investigation and monitoring. In this manuscript we present a method of accurately modeling the effects of buried conductive infrastructure within the forward modeling algorithm, thereby removing them from the inversion results. The method is implemented in parallel using immersed interface boundary conditions, whereby the global solution is reconstructed from a series of well-conditioned partial solutions. Forward modeling accuracy is demonstrated by comparison with analytic solutions. Synthetic imaging examples are used to investigate imaging capabilities within a subsurface containing electrically conductive buried tanks, transfer piping, and well casing, using both well casings and vertical electrode arrays as current sources and potential measurement electrodes. Results show that, although accurate infrastructure modeling removes the dominating influence of buried metallic features, the presence of metallic infrastructure degrades imaging resolution compared to standard ERT imaging. However, accurate imaging results may be obtained if electrodes are appropriately located.

  13. Solid state sensor for locating and imaging sources of gamma and x-radiation

    SciTech Connect

    Kronenberg, S.; Brucker, G.J.; Bechtel, E.

    1998-06-01

    This paper describes the design and characterization of a directional Solid State Detector (SSD) that generates images of radiation point sources and scatter patterns from irradiated targets, thus accurately identifying their locations. Previous papers demonstrated that other types of directional radiation sensors, such as Ionization Chambers, Geiger-Mueller and Scintillation Counters, can be designed to detect and locate arrays of gamma ray and x-ray point sources and broad scatter patterns.

  14. Three precise gamma-ray burst source locations

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Teegarden, B. J.; Barat, C.; Hurley, K.; Niel, M.; Vedrenne, G.; Evans, W. D.; Klebesadel, R. W.; Laros, J. G.

    1984-01-01

    The precise source regions of three moderately intense gamma ray bursts are derived. These events were observed with the first interplanetary burst sensor network. The optimum locations of the detectors, widely separated throughout the inner solar system, allowed for high accuracy, over-determined source fields of size 0.7 to 7.0 arc-min(2). All three locations are at fairly high galactic latitude in regions of low source confusion; none can be identified with a steady source object. Archived photographs were searched for optical transients that are able to be associated with these source fields; one such association was made.

  15. Sequential Optimal Monitoring Network Design using Iterative Kriging for Identification of Unknown Groundwater Pollution Sources Location

    NASA Astrophysics Data System (ADS)

    Prakash, O.; Datta, B.

    2011-12-01

    Identification of unknown groundwater pollution source characteristics, in terms of location, magnitude and activity duration is important for designing an effective pollution remediation strategy. Precise source characterization also becomes very important to ascertain liability, and to recover the cost of remediation from parties responsible for the groundwater pollution. Due to the uncertainties in accurately predicting the aquifer response to source flux injection, generally encountered sparsity of concentration observation data in the field, and the non uniqueness in the aquifer response to the subjected hydraulic and chemical stresses, groundwater pollution source characterization remains a challenging task. A scientifically designed pollutant concentration monitoring network becomes imperative for accurate pollutant source characterization. The efficiency of the unknown source locations identification process is largely determined by locations of monitoring wells where the pollutant concentration is observed. The proposed method combines spatial interpolation of concentration measurements and Simulated Annealing as optimization algorithm to find the optimum locations for monitoring wells. Initially, the observed concentration data at few sparsely and arbitrarily distributed wells are used to interpolate the concentration data for the aquifer study area. The concentration information is passed to the optimization algorithm (decision model) as concentration gradient which in turn finds the optimum locations for implementing the next sequence of monitoring wells. Concentration measurement data from these designed monitoring wells and already implemented monitoring network are iteratively used as feedback information for potential groundwater pollution source locations identification. The potential applicability of the developed methodology is demonstrated for an illustrative study area.

  16. Locating the source of diffusion in complex networks by time-reversal backward spreading

    NASA Astrophysics Data System (ADS)

    Shen, Zhesi; Cao, Shinan; Wang, Wen-Xu; Di, Zengru; Stanley, H. Eugene

    2016-03-01

    Locating the source that triggers a dynamical process is a fundamental but challenging problem in complex networks, ranging from epidemic spreading in society and on the Internet to cancer metastasis in the human body. An accurate localization of the source is inherently limited by our ability to simultaneously access the information of all nodes in a large-scale complex network. This thus raises two critical questions: how do we locate the source from incomplete information and can we achieve full localization of sources at any possible location from a given set of observable nodes. Here we develop a time-reversal backward spreading algorithm to locate the source of a diffusion-like process efficiently and propose a general locatability condition. We test the algorithm by employing epidemic spreading and consensus dynamics as typical dynamical processes and apply it to the H1N1 pandemic in China. We find that the sources can be precisely located in arbitrary networks insofar as the locatability condition is assured. Our tools greatly improve our ability to locate the source of diffusion in complex networks based on limited accessibility of nodal information. Moreover, they have implications for controlling a variety of dynamical processes taking place on complex networks, such as inhibiting epidemics, slowing the spread of rumors, pollution control, and environmental protection.

  17. Locating the source of diffusion in complex networks by time-reversal backward spreading.

    PubMed

    Shen, Zhesi; Cao, Shinan; Wang, Wen-Xu; Di, Zengru; Stanley, H Eugene

    2016-03-01

    Locating the source that triggers a dynamical process is a fundamental but challenging problem in complex networks, ranging from epidemic spreading in society and on the Internet to cancer metastasis in the human body. An accurate localization of the source is inherently limited by our ability to simultaneously access the information of all nodes in a large-scale complex network. This thus raises two critical questions: how do we locate the source from incomplete information and can we achieve full localization of sources at any possible location from a given set of observable nodes. Here we develop a time-reversal backward spreading algorithm to locate the source of a diffusion-like process efficiently and propose a general locatability condition. We test the algorithm by employing epidemic spreading and consensus dynamics as typical dynamical processes and apply it to the H1N1 pandemic in China. We find that the sources can be precisely located in arbitrary networks insofar as the locatability condition is assured. Our tools greatly improve our ability to locate the source of diffusion in complex networks based on limited accessibility of nodal information. Moreover, they have implications for controlling a variety of dynamical processes taking place on complex networks, such as inhibiting epidemics, slowing the spread of rumors, pollution control, and environmental protection. PMID:27078360

  18. 48 CFR 319.202-2 - Locating small business sources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 4 2014-10-01 2014-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 319.202-2 Locating small business sources. (a) OPDIVs shall foster, to the extent practicable, maximum participation by small businesses in HHS...

  19. 48 CFR 319.202-2 - Locating small business sources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 4 2012-10-01 2012-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 319.202-2 Locating small business sources. (a) OPDIVs shall foster, to the extent practicable, maximum participation by small businesses in HHS...

  20. 48 CFR 319.202-2 - Locating small business sources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 4 2013-10-01 2013-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 319.202-2 Locating small business sources. (a) OPDIVs shall foster, to the extent practicable, maximum participation by small businesses in HHS...

  1. 48 CFR 2919.202-2 - Locating small business sources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 7 2013-10-01 2012-10-01 true Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS AND SMALL DISADVANTAGED BUSINESS CONCERNS Policies 2919.202-2 Locating small business sources. Any procurement conducted on an unrestricted basis will include solicitations...

  2. 48 CFR 19.202-2 - Locating small business sources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 19.202-2 Locating small business sources. The contracting officer must, to the extent practicable, encourage maximum participation by small...

  3. 48 CFR 2919.202-2 - Locating small business sources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS AND SMALL DISADVANTAGED BUSINESS CONCERNS Policies 2919.202-2 Locating small business sources. Any procurement conducted on an unrestricted basis will include solicitations...

  4. 48 CFR 19.202-2 - Locating small business sources.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 19.202-2 Locating small business sources. The contracting officer must, to the extent practicable, encourage maximum participation by small...

  5. 48 CFR 319.202-2 - Locating small business sources.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 4 2011-10-01 2011-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 319.202-2 Locating small business sources. (a) OPDIVs... small business concerns that can compete for the proposed requirement—see FAR 19.202, 10.001(2)(v),...

  6. 48 CFR 319.202-2 - Locating small business sources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 319.202-2 Locating small business sources. (a) OPDIVs... small business concerns that can compete for the proposed requirement—see FAR 19.202, 10.001(2)(v),...

  7. 48 CFR 19.202-2 - Locating small business sources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 19.202-2 Locating small business sources. The contracting officer must, to the extent practicable, encourage maximum participation by small...

  8. 48 CFR 2919.202-2 - Locating small business sources.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 7 2011-10-01 2011-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS AND SMALL DISADVANTAGED BUSINESS CONCERNS Policies 2919.202-2 Locating small business sources. Any procurement conducted on an unrestricted basis will include solicitations...

  9. Using XTE as Part of the IPN to Derive Accurate GRB Locations

    NASA Technical Reports Server (NTRS)

    Barthelmy, S.

    1998-01-01

    The objective of this final report was to integrate the Rossi X-Ray Timing Explorer PCA into the 3rd Interplanetary Network of gamma-ray burst detectors, to allow more bursts to be detected and accurately localized. Although the necessary software was implemented to do this at Goddard and at UC Berkeley, several factors made a full integration impossible or impractical.

  10. Locating an atmospheric contamination source using slow manifolds

    NASA Astrophysics Data System (ADS)

    Tang, Wenbo; Haller, George; Baik, Jong-Jin; Ryu, Young-Hee

    2009-04-01

    Finite-size particle motion in fluids obeys the Maxey-Riley equations, which become singular in the limit of infinitesimally small particle size. Because of this singularity, finding the source of a dispersed set of small particles is a numerically ill-posed problem that leads to exponential blowup. Here we use recent results on the existence of a slow manifold in the Maxey-Riley equations to overcome this difficulty in source inversion. Specifically, we locate the source of particles by projecting their dispersed positions on a time-varying slow manifold, and by advecting them on the manifold in backward time. We use this technique to locate the source of a hypothetical anthrax release in an unsteady three-dimensional atmospheric wind field in an urban street canyon.

  11. Accurate identification of centromere locations in yeast genomes using Hi-C.

    PubMed

    Varoquaux, Nelle; Liachko, Ivan; Ay, Ferhat; Burton, Joshua N; Shendure, Jay; Dunham, Maitreya J; Vert, Jean-Philippe; Noble, William S

    2015-06-23

    Centromeres are essential for proper chromosome segregation. Despite extensive research, centromere locations in yeast genomes remain difficult to infer, and in most species they are still unknown. Recently, the chromatin conformation capture assay, Hi-C, has been re-purposed for diverse applications, including de novo genome assembly, deconvolution of metagenomic samples and inference of centromere locations. We describe a method, Centurion, that jointly infers the locations of all centromeres in a single genome from Hi-C data by exploiting the centromeres' tendency to cluster in three-dimensional space. We first demonstrate the accuracy of Centurion in identifying known centromere locations from high coverage Hi-C data of budding yeast and a human malaria parasite. We then use Centurion to infer centromere locations in 14 yeast species. Across all microbes that we consider, Centurion predicts 89% of centromeres within 5 kb of their known locations. We also demonstrate the robustness of the approach in datasets with low sequencing depth. Finally, we predict centromere coordinates for six yeast species that currently lack centromere annotations. These results show that Centurion can be used for centromere identification for diverse species of yeast and possibly other microorganisms. PMID:25940625

  12. Hyperbolic source location of crack related acoustic emission in bone.

    PubMed

    O'Toole, John; Creedon, Leo; Hession, John; Muir, Gordon

    2013-01-01

    Little work has been done on the localization of microcracks in bone using acoustic emission. Microcrack localization is useful to study the fracture process in bone and to prevent fractures in patients. Locating microcracks that occur before fracture allows one to predict where fracture will occur if continued stress is applied to the bone. Two source location algorithms were developed to locate microcracks on rectangular bovine bone samples. The first algorithm uses a constant velocity approach which has some difficulty dealing with the anisotropic nature of bone. However, the second algorithm uses an iterative technique to estimate the correct velocity for the acoustic emission source location being located. In tests with simulated microcracks, the constant velocity algorithm achieves a median error of 1.78 mm (IQR 1.51 mm) and the variable velocity algorithm improves this to a median error of 0.70 mm (IQR 0.79 mm). An experiment in which the bone samples were loaded in a three point bend test until they fractured showed a good correlation between the computed location of detected microcracks and where the final fracture occurred. Microcracks can be located on bovine bone samples using acoustic emission with good accuracy and precision. PMID:23363217

  13. Shallow-water sparsity-cognizant source-location mapping.

    PubMed

    Forero, Pedro A; Baxley, Paul A

    2014-06-01

    Using passive sonar for underwater acoustic source localization in a shallow-water environment is challenging due to the complexities of underwater acoustic propagation. Matched-field processing (MFP) exploits both measured and model-predicted acoustic pressures to localize acoustic sources. However, the ambiguity surface obtained through MFP contains artifacts that limit its ability to reveal the location of the acoustic sources. This work introduces a robust scheme for shallow-water source localization that exploits the inherent sparse structure of the localization problem and the use of a model characterizing the acoustic propagation environment. To this end, the underwater acoustic source-localization problem is cast as a sparsity-inducing stochastic optimization problem that is robust to model mismatch. The resulting source-location map (SLM) yields reduced ambiguities and improved resolution, even at low signal-to-noise ratios, when compared to those obtained via classical MFP approaches. An iterative solver based on block-coordinate descent is developed whose computational complexity per iteration is linear with respect to the number of locations considered for the SLM. Numerical tests illustrate the performance of the algorithm. PMID:24907812

  14. Providing Source-Location Privacy in Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Li, Yun; Ren, Jian

    Wireless sensor networks (WSN) have been widely used in many areas for unattended event monitoring. Mainly due to lack of a protected physical boundary, wireless communications are vulnerable to unauthorized detection, interception and and even node capture. Privacy is becoming one of the major issues that jeopardize the successful deployment and survivability of wireless sensor networks. While confidentiality of the message can be ensured through content encryption, it is much more difficult to adequately address the source-location privacy. For WSN, source-location privacy service is further complicated by the fact that the sensor nodes consist of low-cost and low-power radio devices, computationally intensive cryptographic algorithms (such as public-key cryptosystems) and large scale broadcasting-based protocols are not suitable for WSN. In this paper, we propose a two-step routing strategy for the messages to be routed from the actual source node to the SINK node through either a single, or multiple, randomly selected intermediate node(s) away from the source node so that it is to make it infeasible for the adversaries to trace back to the source node through hop-by-hop routing analysis. In the first protocol, the messages will be routed to a single intermediate node. This scheme can provide very good local source-location privacy. We also propose routing through multiple randomly selected intermediate nodes based on angle and quadrant to further improve the performance and security. While providing source-location privacy for WSN, our simulation results demonstrate that the proposed schemes are very efficient in energy consumption, and transmission latency. The proposed schemes can also assurance high message delivery ratio. Therefore, they can be used for many practical applications.

  15. Locating and estimating air emissions from sources of nickel

    SciTech Connect

    Not Available

    1984-03-01

    To assist groups interested in inventorying air emissions of various potentially toxic substances, EPA is preparing a series of documents such as this to compile available information on sources and emissions of these substances. This document deals specifically with nickel. Its intended audience includes Federal, State and local air pollution personnel and others interested in locating potential emitters of nickel and in making gross estimates of air emissions therefrom. This document presents information on (1) the types of sources that may emit nickel, (2) process variations and release points that may be expected within these sources, and (3) available emissions information indicating the potential for nickel release into the air from each operation.

  16. Use of Loran-C navigation system to accurately determine sampling site location in an above ground cooling reservoir

    SciTech Connect

    Lockwood, R.E.; Blankinship, D.R.

    1994-12-31

    Environmental monitoring programs often require accurate determination of sampling site locations in aquatic environments. This is especially true when a {open_quotes}picture{close_quotes} of high resolution is needed for observing a changing variable in a given area and location is assumed to be important to the distribution of that variable. Sample site location can be difficult if few visible land marks are available for reference on a large body of water. The use of navigational systems such as Global Positioning System (GPS) and its predecessor, Loran-C, provide an excellent method for sample site location. McFarland (1992) discusses the practicality of GPS for location determination. This article discusses the use of Loran-C in a sampling scheme implemented at the South Texas Project Electrical Generating Station (STPEGS), Wadsworth, Texas.

  17. Modeling of Jovian Hectometric Radiation Source Locations: Ulysses Observations

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Reiner, M. J.

    1996-01-01

    The Unified Radio and Plasma Wave (URAP) experiment on Ulysses has provided unique high latitude measurements of Jovian hectometric radiation (HOM) during its encounter with Jupiter in February 1992. URAP was the first radio instrument in the Jovian environment with radio direction-finding capability, which was previously used to determine the HOM source locations in the Jovian magnetosphere. These initial source location determinations were based on several assumptions, including the neglect of refractive effects, which may be tested. We have, for the first time, combined the measured incident ray-direction at the spacecraft with a model magnetosphere to directly trace the rays back to the HOM source. We concentrate on the observations of HOM from high northern latitudes when Ulysses was at distances less than 15 R(sub j). The three- dimensional ray-tracing calculations presented here indicate that the HOM sources probably lie on L shells in the range 3 less than or approximately equal to L less than 7 (tilted dipole magnetic field model) consistent with previous determinations that ignored the effects of refraction. The ray-tracing results, however, indicate that wave refraction due to the Io torus and the magnetic field can significantly influence the precise source location. We show that constraints on the locations imposed by the gyroemission mechanism suggest that the lo torus density may have experienced temporal and/or spatial fluctuations during the Ulysses observations of HOM. Finally, in the cold plasma approximation we demonstrate that even if the emission were nearly linearly polarized near the source region, almost circular polarization will be observed at Ulysses, in agreement with observations.

  18. Accurate estimation of object location in an image sequence using helicopter flight data

    NASA Technical Reports Server (NTRS)

    Tang, Yuan-Liang; Kasturi, Rangachar

    1994-01-01

    In autonomous navigation, it is essential to obtain a three-dimensional (3D) description of the static environment in which the vehicle is traveling. For a rotorcraft conducting low-latitude flight, this description is particularly useful for obstacle detection and avoidance. In this paper, we address the problem of 3D position estimation for static objects from a monocular sequence of images captured from a low-latitude flying helicopter. Since the environment is static, it is well known that the optical flow in the image will produce a radiating pattern from the focus of expansion. We propose a motion analysis system which utilizes the epipolar constraint to accurately estimate 3D positions of scene objects in a real world image sequence taken from a low-altitude flying helicopter. Results show that this approach gives good estimates of object positions near the rotorcraft's intended flight-path.

  19. PM(10) source characterization at urban and highway roadside locations.

    PubMed

    Furusjö, Erik; Sternbeck, John; Cousins, Anna Palm

    2007-11-15

    Levels of PM(10) were measured at two different roadside locations in the Stockholm region in Sweden, one highway south of Stockholm and one urban street canyon in the center of the city. PM(10) samples were taken during six separate campaigns over one full year, and analyzed for 29 metals, in order to help characterize sources of PM(10). Five contributing factors were identified by multivariate receptor modeling using positive matrix factorization. Factors were classified, based on their seasonal variation and published data on metal composition of different sources, as: 1) resuspension; 2) vehicle derived; 3) road salt; 4) regional combustion and 5) long-range transport. Resuspension and long-range transport were shown to be important contributors to the PM(10) levels at both sites. In fact, long-range transport was the main contributor to the PM(10) levels at the highway roadside. The vehicle source was only of major importance at the urban roadside, where it frequently contributed between 10 and 20 microg m(-3). Brake wear was an important component in the vehicle source. Vehicle exhaust was not detected as a separate source and was not identified as a major source for PM(10). To our knowledge, this is the first study identifying brake wear as a major source of PM(10) during urban driving. PMID:17822744

  20. Acoustic emission source location in complex structures using full automatic delta T mapping technique

    NASA Astrophysics Data System (ADS)

    Al-Jumaili, Safaa Kh.; Pearson, Matthew R.; Holford, Karen M.; Eaton, Mark J.; Pullin, Rhys

    2016-05-01

    An easy to use, fast to apply, cost-effective, and very accurate non-destructive testing (NDT) technique for damage localisation in complex structures is key for the uptake of structural health monitoring systems (SHM). Acoustic emission (AE) is a viable technique that can be used for SHM and one of the most attractive features is the ability to locate AE sources. The time of arrival (TOA) technique is traditionally used to locate AE sources, and relies on the assumption of constant wave speed within the material and uninterrupted propagation path between the source and the sensor. In complex structural geometries and complex materials such as composites, this assumption is no longer valid. Delta T mapping was developed in Cardiff in order to overcome these limitations; this technique uses artificial sources on an area of interest to create training maps. These are used to locate subsequent AE sources. However operator expertise is required to select the best data from the training maps and to choose the correct parameter to locate the sources, which can be a time consuming process. This paper presents a new and improved fully automatic delta T mapping technique where a clustering algorithm is used to automatically identify and select the highly correlated events at each grid point whilst the "Minimum Difference" approach is used to determine the source location. This removes the requirement for operator expertise, saving time and preventing human errors. A thorough assessment is conducted to evaluate the performance and the robustness of the new technique. In the initial test, the results showed excellent reduction in running time as well as improved accuracy of locating AE sources, as a result of the automatic selection of the training data. Furthermore, because the process is performed automatically, this is now a very simple and reliable technique due to the prevention of the potential source of error related to manual manipulation.

  1. Accurate location of nuclear explosions at Azgir, Kazakhstan, from satellite images and seismic data: Implications for monitoring decoupled explosions

    NASA Astrophysics Data System (ADS)

    Sykes, Lynn R.; Deng, Jishu; Lyubomirskiy, Paul

    1993-09-01

    The 10 largest tamped nuclear explosions detonated by the Former Soviet Union in and near two salt domes near Azgir were relocated using seismic data and the locations of shot points on a SPOT satellite image taken in 1988. Many of the shot points are clearly recognized on the satellite image and can be located with an accuracy of 60 m even though testing was carried out at those points many years earlier, i. e. between 1966 and 1979. Onsite inspections and a local seismic monitoring network combined with our accurate locations of previous explosions would insure that any cavities that remain standing from those events could not be used for undetected decoupled nuclear testing down to a very small yield. Since the Azgir area, like much of the Pre-Caspian depression, is arid, it would not be a suitable place for constructing large cavities in salt by solution mining and then using them for clandestine nuclear testing.

  2. Locating the Source of Diffusion in Large-Scale Networks

    NASA Astrophysics Data System (ADS)

    Pinto, Pedro C.; Thiran, Patrick; Vetterli, Martin

    2012-08-01

    How can we localize the source of diffusion in a complex network? Because of the tremendous size of many real networks—such as the internet or the human social graph—it is usually unfeasible to observe the state of all nodes in a network. We show that it is fundamentally possible to estimate the location of the source from measurements collected by sparsely placed observers. We present a strategy that is optimal for arbitrary trees, achieving maximum probability of correct localization. We describe efficient implementations with complexity O(Nα), where α=1 for arbitrary trees and α=3 for arbitrary graphs. In the context of several case studies, we determine how localization accuracy is affected by various system parameters, including the structure of the network, the density of observers, and the number of observed cascades.

  3. Locating tritium sources in a research reactor building.

    PubMed

    Fukui, Masami

    2005-10-01

    Despite renovation of the D2O facility, tritium concentrations in the condensates of reactor room air showed tens of Bq mL before venting resumption on July 1997. This suggested the presence of tritium sources in the research reactor-containment building. An investigation was therefore initiated to locate the source and determine the distribution of tritium in the containment building. Air monitoring in the working area using a dish of water placed in the building suggested that the source of tritium was near the reactor core. Monitoring exhaust air from the two facilities (a cold neutron source and a D(2)O tank) showed high specific activity on the order of 10 Bq mL(-1), suggesting the presence of tritium in condensates near the reactor core. The major concern was whether the leakage of liquid deuterium (4 L) and heavy water (2 x 10(3) L) used as a moderator had occurred. The concentration of tritium in condensates has not increased over the past few years in either the exhaust line or working area, and the deuterium itself has not been found in the surrounding environment. The concentration of tritium measured using an ionization chamber after Ar decay was dependent on the thermal output of the research reactor, indicating that the tritium was produced by the irradiation process within shielding/moderator materials or cover gas with neutrons. PMID:16155451

  4. Possible Source Location of the Terrestrial Myriametric Radio Burst

    NASA Astrophysics Data System (ADS)

    Fung, S. F.; Shao, X.; Frey, H. U.; Garcia, L. N.

    2013-12-01

    Fung et al. [2013] reported recently the identification of a terrestrial myriametric radio burst (TMRB) that was possibly a result from a dayside high latitude reconnection process. The TMRB was observed simultaneously by the IMAGE and Geotail satellites when the satellites were located at widely different latitudes on opposite sides of the Earth in nearly the same meridional plane. The TMRB was observed when the interplanetary field was northward. Its intensity seemed to be modulated by the IMF Bz component while the source directions (relative to the Geotail positions over the TMRB interval) also seemed to respond to the changes in the IMF By component. In this paper, we will present further observations from the IMAGE FUV data during the TMRB interval, revealing the presence of a bright proton aurora spot at the cusp foot print and thus confirming the presence of high-latitude dayside reconnection at the time. We have also performed a CCMC run-on-request of a global magnetospheric simulation for a time period over the TMRB interval. We will present the CCMC results and discuss the possible identification of the location of the TMRB source. Fung, S. F., K. Hashimoto, H. Kojima, S. A. Boardsen, L. N. Garcia, H. Matsumoto, J. L. Green, and B. W. Reinisch (2013), Terrestrial myriametric radio burst observed by IMAGE and Geotail satellites, J. Geophys. Res. Space Physics, 118, 1101-1111, doi:10.1002/jgra.50149.

  5. Structural health monitoring of liquid-filled tanks: a Bayesian approach for location of acoustic emission sources

    NASA Astrophysics Data System (ADS)

    Zárate, Boris A.; Pollock, Adrian; Momeni, Sepand; Ley, Obdulia

    2015-01-01

    Acoustic emission (AE) is a well-established nondestructive testing method for assessing the condition of liquid-filled tanks. Often the tank can be tested without the need for accurate location of AE sources. But sometimes, accurate location is required, such as in the case of follow-up inspections after AE has indicated a significant defect. Traditional computed location techniques that considered only the wave traveling through the shell of the tank have not proved reliable when applied to liquid-filled tanks. This because AE sensors are often responding to liquid-borne waves, that are not considered in the traditional algorithms. This paper describes an approach for locating AE sources on the wall of liquid filled tanks that includes two novel aspects: (i) the use of liquid-borne waves, and (ii) the use of a probabilistic algorithm. The proposed algorithm is developed within a Bayesian framework that considers uncertainties in the wave velocities and the time of arrival. A Markov Chain Monte Carlo is used to estimate the distribution of the AE source location. This approach was applied on a 102 inch diameter (29 000 gal) railroad tank car by estimating the source locations from pencil lead break with waveforms recorded. Results show that the proposed Bayesian approach for source location can be used to calculate the most probable region of the tank wall where the AE source is located.

  6. Location of the effective diffusing-photon source in a strongly scattering medium.

    PubMed

    Kostko, A F; Pavlov, V A

    1997-10-20

    When a narrow laser beam illuminates a strongly scattering medium, the effective pointlike source of diffusing photons appears inside the medium. By the method worked out, which is based on measurements of the diffusive intensity of light emerging from a turbid spherical sample, the depth of this source site (the penetration depth) is determined relatively to the sample diameter, which is known accurately. By using this method of locating the effective source, we have discovered that its position inside the medium is unexpectedly deep. We obtained the penetration depth D(0) = 4.6 l* +/- 0.7 l* instead of one transport mean free path, where l* is the value of D(0) in the standard diffusion theory. Information about this source dipping is useful in diffusing-photon correlation spectroscopy because of its influence on the geometric factor calculated from the diffusion equation. PMID:18264271

  7. Fracture source location in thin plates using the wavelet transform of dispersive waves.

    PubMed

    Jeong, H; Jang, Y S

    2000-01-01

    A new signal processing approach was presented for acoustic emission source location using the dispersive waves in a thin plate. For wave propagation in dispersive media, the accuracy of source location can be improved by using the arrival times of a single frequency component in the output signals at an array of sensors. The wavelet transform (WT) was used to resolve this problem. By utilizing the time-frequency data of the WT, the frequency-dependent arrival time traveling with the group velocity was shown to be easily determined. Experiments were performed using a lead break as the simulated fracture source on the surface of an aluminum plate. Two plate modes corresponding to the S(0) and A(0) Lamb waves were identified, and their group velocities were accurately measured. The source location results based on the WT method agreed well with the true locations. The WT method was also compared with the cross correlation technique, and both methods provide similar results. PMID:18238588

  8. Neptune's non-thermal radio emissions - Phenomenology and source locations

    NASA Technical Reports Server (NTRS)

    Rabl, Gerald K. F.; Ladreiter, H.-P.; Rucker, Helmut O.; Kaiser, Michael L.

    1992-01-01

    During the inbound and the outbound leg of Voyager 2's encounter with Neptune, the Planetary Radio Astronomy (PRA) experiment aboard the spacecraft detected short radio bursts at frequencies within the range of about 500-1300 kHz, and broad-banded smoothly varying emission patterns within the frequency range from about 40-800 kHz. Both emissions can be described in terms of a period of 16.1 hours determining Neptune's rotation period. Furthermore, just near closest approach, a narrow-banded smoothly varying radio component was observed occurring between 600 and 800 kHz. After giving a brief overview about some general characteristics of Neptune's nonthermal radio emission, the source locations of Neptune's emission components are determined, using an offset tilted dipole model for Neptune's magnetic field. Assuming that the emission originates near the electron gyrofrequency a geometrical beaming model is developed in order to fit the observed emission episodes.

  9. Accurate Analysis of the Change in Volume, Location, and Shape of Metastatic Cervical Lymph Nodes During Radiotherapy

    SciTech Connect

    Takao, Seishin; Tadano, Shigeru; Taguchi, Hiroshi; Yasuda, Koichi; Onimaru, Rikiya; Ishikawa, Masayori; Bengua, Gerard; Suzuki, Ryusuke; Shirato, Hiroki

    2011-11-01

    Purpose: To establish a method for the accurate acquisition and analysis of the variations in tumor volume, location, and three-dimensional (3D) shape of tumors during radiotherapy in the era of image-guided radiotherapy. Methods and Materials: Finite element models of lymph nodes were developed based on computed tomography (CT) images taken before the start of treatment and every week during the treatment period. A surface geometry map with a volumetric scale was adopted and used for the analysis. Six metastatic cervical lymph nodes, 3.5 to 55.1 cm{sup 3} before treatment, in 6 patients with head and neck carcinomas were analyzed in this study. Three fiducial markers implanted in mouthpieces were used for the fusion of CT images. Changes in the location of the lymph nodes were measured on the basis of these fiducial markers. Results: The surface geometry maps showed convex regions in red and concave regions in blue to ensure that the characteristics of the 3D tumor geometries are simply understood visually. After the irradiation of 66 to 70 Gy in 2 Gy daily doses, the patterns of the colors had not changed significantly, and the maps before and during treatment were strongly correlated (average correlation coefficient was 0.808), suggesting that the tumors shrank uniformly, maintaining the original characteristics of the shapes in all 6 patients. The movement of the gravitational center of the lymph nodes during the treatment period was everywhere less than {+-}5 mm except in 1 patient, in whom the change reached nearly 10 mm. Conclusions: The surface geometry map was useful for an accurate evaluation of the changes in volume and 3D shapes of metastatic lymph nodes. The fusion of the initial and follow-up CT images based on fiducial markers enabled an analysis of changes in the location of the targets. Metastatic cervical lymph nodes in patients were suggested to decrease in size without significant changes in the 3D shape during radiotherapy. The movements of the

  10. Successful cuing of gender source memory does not improve location source memory.

    PubMed

    Hicks, Jason L; Starns, Jeffrey J

    2016-05-01

    In three experiments we explored cross-dimensional cuing effects in a multidimensional source encoding and retrieval paradigm. We employed a bias-controlled experimental method of source cuing at retrieval (Starns & Hicks, 2013) in an attempt to improve retrieval of location information indirectly by cuing gender information. Encoded words were situated on the left or right side of a computer monitor and associated with either a male or a female face. When multiple faces were used across the set of encoded words, reinstating the correct face at retrieval alongside an incorrect, opposite-gender face cue improved male/female source decisions for test words. However, this powerful test cue did not improve memory for the encoded location of the words, suggesting that within-dimension cuing does not produce cross-dimensional cuing. This null outcome was found when gender decisions were required (Experiments 1A and 2) or not required (Experiment 1B) prior to location decisions. Nor was cross-dimension cuing found when subjects were told to expect a source test of both gender and location information at retrieval (Experiment 2). Our findings reinforce prior work demonstrating that multiple context dimensions can be bound to item information without any direct binding between the contexts. PMID:26810799

  11. Airborne system for detection and location of radio interference sources

    NASA Astrophysics Data System (ADS)

    Audone, Bruno; Pastore, Alberto

    1992-11-01

    The rapid expansion of telecommunication has practically saturated every band of Radio Frequency Spectrum; a similar expansion of electrical and electronic devices has affected all radio communications which are, in some way, influenced by a large amount of interferences, either intentionally or unintentionally produced. Operational consequences of these interferences, particularly in the frequency channels used for aeronautical services, can be extremely dangerous, making mandatory a tight control of Electromagnetic Spectrum. The present paper analyzes the requirements and the problems related to the surveillance, for civil application, of the Electromagnetic Spectrum between 20 and 1000 MHz, with particular attention to the detection and location of radio interference sources; after a brief introduction and the indication of the advantages of an airborne versus ground installation, the airborne system designed by Alenia in cooperation with Italian Ministry of Post and Telecommunication, its practical implementation and the prototype installation on board of a small twin turboprop aircraft for experimentation purposes is presented. The results of the flight tests are also analyzed and discussed.

  12. Travel-time source-specific station correction improves location accuracy

    NASA Astrophysics Data System (ADS)

    Giuntini, Alessandra; Materni, Valerio; Chiappini, Stefano; Carluccio, Roberto; Console, Rodolfo; Chiappini, Massimo

    2013-04-01

    Accurate earthquake locations are crucial for investigating seismogenic processes, as well as for applications like verifying compliance to the Comprehensive Test Ban Treaty (CTBT). Earthquake location accuracy is related to the degree of knowledge about the 3-D structure of seismic wave velocity in the Earth. It is well known that modeling errors of calculated travel times may have the effect of shifting the computed epicenters far from the real locations by a distance even larger than the size of the statistical error ellipses, regardless of the accuracy in picking seismic phase arrivals. The consequences of large mislocations of seismic events in the context of the CTBT verification is particularly critical in order to trigger a possible On Site Inspection (OSI). In fact, the Treaty establishes that an OSI area cannot be larger than 1000 km2, and its larger linear dimension cannot be larger than 50 km. Moreover, depth accuracy is crucial for the application of the depth event screening criterion. In the present study, we develop a method of source-specific travel times corrections based on a set of well located events recorded by dense national seismic networks in seismically active regions. The applications concern seismic sequences recorded in Japan, Iran and Italy. We show that mislocations of the order of 10-20 km affecting the epicenters, as well as larger mislocations in hypocentral depths, calculated from a global seismic network and using the standard IASPEI91 travel times can be effectively removed by applying source-specific station corrections.

  13. Source location of the narrowbanded radio bursts at Uranus - Evidence of a cusp source

    NASA Astrophysics Data System (ADS)

    Farrell, W. M.; Desch, M. D.; Kaiser, M. L.; Kurth, W. S.

    1990-03-01

    While Voyager 2 was inbound to Uranus, radio bursts of narrow bandwidth (less than 5 kHz) were detected between 17-116 kHz. These R-X mode bursts, designated n-bursts, were of short duration, tended to occur when the north magnetic pole tipped toward the spacecraft, and increased in occurrence with increasing solar wind density. An explicit determination of the burst source location is presented, based upon fitting the region of detection at high and low frequencies to field-aligned, symmetric cones. The region of good fits was located between the north magnetic pole and the rotational pole, corresponding approximately to the northern polar cusp.

  14. Finding faces among faces: human faces are located more quickly and accurately than other primate and mammal faces.

    PubMed

    Simpson, Elizabeth A; Buchin, Zachary; Werner, Katie; Worrell, Rey; Jakobsen, Krisztina V

    2014-11-01

    We tested the specificity of human face search efficiency by examining whether there is a broad window of detection for various face-like stimuli-human and animal faces-or whether own-species faces receive greater attentional allocation. We assessed the strength of the own-species face detection bias by testing whether human faces are located more efficiently than other animal faces, when presented among various other species' faces, in heterogeneous 16-, 36-, and 64-item arrays. Across all array sizes, we found that, controlling for distractor type, human faces were located faster and more accurately than primate and mammal faces, and that, controlling for target type, searches were faster when distractors were human faces compared to animal faces, revealing more efficient processing of human faces regardless of their role as targets or distractors (Experiment 1). Critically, these effects remained when searches were for specific species' faces (human, chimpanzee, otter), ruling out a category-level explanation (Experiment 2). Together, these results suggest that human faces may be processed more efficiently than animal faces, both when task-relevant (targets) and task-irrelevant (distractors), even in direct competition with other faces. These results suggest that there is not a broad window of detection for all face-like patterns but that human adults process own-species' faces more efficiently than other species' faces. Such own-species search efficiencies may arise through experience with own-species faces throughout development or may be privileged early in development, due to the evolutionary importance of conspecifics' faces. PMID:25113852

  15. High-precision source location of the 1978 November 19 gamma-ray burst

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Teegarden, B. J.; Pizzichini, G.; Evans, W. D.; Klebesadel, R. W.; Laros, J. G.; Barat, C.; Hurley, K.; Niel, M.

    1981-01-01

    The celestial source location of the November 19, 1978, intense gamma ray burst has been determined from data obtained with the interplanetary gamma-ray sensor network by means of long-baseline wave front timing instruments. Each of the instruments was designed for studying events with observable spectra of approximately greater than 100 keV, and each provides accurate event profile timing in the several millisecond range. The data analysis includes the following: the triangulated region is centered at (gamma, delta) 1950 = (1h16m32s, -28 deg 53 arcmin), at -84 deg galactic latitude, where the star density is very low and the obscuration negligible. The gamma-ray burst source region, consistent with that of a highly polarized radio source described by Hjellming and Ewald (1981), may assist in the source modeling and may facilitate the understanding of the source process. A marginally identifiable X-ray source was also found by an Einstein Observatory investigation. It is concluded that the burst contains redshifted positron annihilation and nuclear first-excited iron lines, which is consistent with a neutron star origin.

  16. 48 CFR 2919.202-2 - Locating small business sources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... small businesses of each category with legislatively established government-wide procurement goals (e.g... businesses) to the extent practicable. ... 48 Federal Acquisition Regulations System 7 2014-10-01 2014-10-01 false Locating small...

  17. 48 CFR 2919.202-2 - Locating small business sources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... small businesses of each category with legislatively established government-wide procurement goals (e.g... businesses) to the extent practicable. ... 48 Federal Acquisition Regulations System 7 2012-10-01 2012-10-01 false Locating small...

  18. Disambiguating past events: Accurate source memory for time and context depends on different retrieval processes.

    PubMed

    Persson, Bjorn M; Ainge, James A; O'Connor, Akira R

    2016-07-01

    Current animal models of episodic memory are usually based on demonstrating integrated memory for what happened, where it happened, and when an event took place. These models aim to capture the testable features of the definition of human episodic memory which stresses the temporal component of the memory as a unique piece of source information that allows us to disambiguate one memory from another. Recently though, it has been suggested that a more accurate model of human episodic memory would include contextual rather than temporal source information, as humans' memory for time is relatively poor. Here, two experiments were carried out investigating human memory for temporal and contextual source information, along with the underlying dual process retrieval processes, using an immersive virtual environment paired with a 'Remember-Know' memory task. Experiment 1 (n=28) showed that contextual information could only be retrieved accurately using recollection, while temporal information could be retrieved using either recollection or familiarity. Experiment 2 (n=24), which used a more difficult task, resulting in reduced item recognition rates and therefore less potential for contamination by ceiling effects, replicated the pattern of results from Experiment 1. Dual process theory predicts that it should only be possible to retrieve source context from an event using recollection, and our results are consistent with this prediction. That temporal information can be retrieved using familiarity alone suggests that it may be incorrect to view temporal context as analogous to other typically used source contexts. This latter finding supports the alternative proposal that time since presentation may simply be reflected in the strength of memory trace at retrieval - a measure ideally suited to trace strength interrogation using familiarity, as is typically conceptualised within the dual process framework. PMID:27174312

  19. A comparison between accurate radio and optical positions for six Southern Hemisphere extragalactic sources

    NASA Astrophysics Data System (ADS)

    Jauncey, David L.; White, Graeme L.; Preston, Robert A.; Niell, Arthur E.; Harvey, Bruce R.; Morabito, David D.; Meier, David L.; Slade, Martin A.; Stolz, Artur; Tzioumis, Anastasios K.

    1989-07-01

    Radio positions measured on a 275 km baseline are given for six extragalactic sources south of declination -45°. The measurements were made using very long baseline interferometry (VLBI) at 2.3 and 8.4 GHz between the 64 m antennas at Parkes and Tidbinbilla, Australia. Positions with accuracies of ±0.11 arcsec in right ascension and ±0.08 arcsec in declination are given with respect to the JPL VLBI reference frame. This program is a first step in establishing an accurate radio reference frame in the mid-latitude to polar regions of the southern hemisphere. Accurate optical positions have also been determined from glass plate copies of the ESO B Schmidt atlas using reference stars from the Perth 70 catalog. A comparison between the optical and radio positions yields mean differences (optical - radio) of -0.02 ± 0.09 and 0.05 ± 0.13 arcsec in right ascension and declination, respectively. On average, the optical reference frame south of -45°, the FK4 as defined by the Perth 70 catalog, and the VLBI radio reference frame as defined by the present six sources, appear to be consistent at the tenth of an arcsecond level.

  20. Source location of the narrowbanded radio bursts at Uranus: Evidence of a cusp source

    SciTech Connect

    Farrell, W.M.; Desch, M.D.; Kaiser, M.L. ); Kurth, W.S. )

    1990-03-01

    While Voyager 2 was inbound to Uranus, radio bursts of narrow bandwidth (< 5 kHz) were detected between 17-116 kHz by both the Planetary Radio Astronomy (PRA) and Plasma Wave (PWS) experiments. These R-X mode bursts, designated n-bursts, were of short duration (about 250 msec), tended to occur when the north magnetic pole tipped toward the spacecraft, and increased in occurrence with increasing solar wind density. In this report, the authors present an explicit determination of the burst source location based upon fitting the region of detection at high and low frequencies to field-aligned, symmetric cones. The region of good fits was located between the north magnetic pole an the rotational pole, corresponding approximately to the northern polar cusp. Based upon the emission power, it is suspected that at certain times large amounts of auroral input power may originate in this cusp.

  1. Locating the acoustic source in thin glass plate using low sampling rate data.

    PubMed

    Hoseini Sabzevari, S Amir; Moavenian, Majid

    2016-08-01

    Acoustic source localization is an important step for structural health monitoring (SHM). There are many research studies dealing with localization based on high sampling rate data. In this paper, for the first time, acoustic source is localized on an isotropic plate using low sampling rate data. Previous studies have mainly used a cluster of specific sensors to easily record high sampling rate signals containing qualitative time domain features. This paper proposes a novel technique to localize the acoustic source on isotropic plates by simply implementing a combination of two simple electret microphones and Loci of k-Tuple Distances (LkTD) from the two sensors with low sampling rate data. In fact the method proposes substitution of previous methods based on solving the system of equations and increasing the number of sensors by implementing the selection of LkTD. Unlike most previous studies, estimation of time difference of arrival (TDOA) is based on the frequency properties of the signal rather than it's time properties. An experimental set-up is prepared and experiments are conducted to validate the proposed technique by prediction of the acoustic source location. The experimental results show that TDOA estimations based on low sampling rate data can produce more accurate predictions in comparison with previous studies. It is also shown that the selection of LkTD on the plate has noticeable effects on the performance of this technique. PMID:27110914

  2. The source location of certain Jovian decametric radio emissions

    NASA Technical Reports Server (NTRS)

    Calvert, W.

    1983-01-01

    Evidence is presented which supports the concept that certain of the Jovian decametric radio waves originate as northern hemisphere extraordinary mode cyclotron emissions. The wave signals received by Voyager 1 near 10 MHz shortly after the closest approach to Jupiter were found to exhibit cusps in the fringe pattern which can be attributed to Faraday rotation in the Io plasma torus. At nearly the same time, the wave polarization near 1 MHz was found to exhibit a sudden reversal of its rotation sense, indicating that the wave path for those frequencies had also become perpendicular to the magnetic field at the spacecraft. It was determined that the waves came from the northern hemisphere at progressively lower altitudes with increasing frequency, and if the source is assumed to be associated with an L = 6 field line, the emission appears to have occurred near the source cyclotron frequency somewhere in the local midnight sector. The evidence indicates that the source is at the Io flux tube and that the emitted wave mode must have been extraordinary. In addition, the emitted wave polarization must have been substantially noncircular which would require a low plasma density near the source, much like that which occurs with auroral kilometric radiation at the earth.

  3. Locating Supplemental Sources of Revenue to Finance Universities in Nigeria.

    ERIC Educational Resources Information Center

    Ogunla, Akin L.

    1989-01-01

    Identifies possible sources of supplemental income to finance Nigerian universities, including households and commercial and industrial firms. A consumption tax imposed on certain goods and services would generate needed funds. Also, because firms employ university graduates to earn higher profits, their turnover income should be taxed to support…

  4. Canonical Decomposition of Ictal Scalp EEG and Accurate Source Localisation: Principles and Simulation Study

    PubMed Central

    De Vos, Maarten; De Lathauwer, Lieven; Vanrumste, Bart; Van Huffel, Sabine; Van Paesschen, W.

    2007-01-01

    Long-term electroencephalographic (EEG) recordings are important in the presurgical evaluation of refractory partial epilepsy for the delineation of the ictal onset zones. In this paper, we introduce a new concept for an automatic, fast, and objective localisation of the ictal onset zone in ictal EEG recordings. Canonical decomposition of ictal EEG decomposes the EEG in atoms. One or more atoms are related to the seizure activity. A single dipole was then fitted to model the potential distribution of each epileptic atom. In this study, we performed a simulation study in order to estimate the dipole localisation error. Ictal dipole localisation was very accurate, even at low signal-to-noise ratios, was not affected by seizure activity frequency or frequency changes, and was minimally affected by the waveform and depth of the ictal onset zone location. Ictal dipole localisation error using 21 electrodes was around 10.0 mm and improved more than tenfold in the range of 0.5–1.0 mm using 148 channels. In conclusion, our simulation study of canonical decomposition of ictal scalp EEG allowed a robust and accurate localisation of the ictal onset zone. PMID:18301715

  5. Type III radio source located by Ulysses/Wind triangulation

    NASA Astrophysics Data System (ADS)

    Reiner, M. J.; Fainberg, J.; Kaiser, M. L.; Stone, R. G.

    1998-02-01

    Radio triangulation from the widely separated Ulysses and Wind spacecraft is used to reconstruct the trajectory of a type III radio burst in the 3D heliosphere. The derived radio trajectory follows a (Parker) spiral path corresponding to a solar wind speed of about 200 km/s and progresses to the south of the ecliptic plane. These remote radio observations also measure the interplanetary plasma density along the path of the radio source. The derived average density-distance scale is very similar to the previously derived RAE density scale, which was determined in a different way. The results of the radio triangulation, combined with a drift rate analysis, give an average electron exciter speed of about 0.3 c. The radio source size and the brightness temperature as viewed from Ulysses and Wind are determined and compared as a function of observing frequency.

  6. 43 CFR 3746.1 - Mining locations for fissionable source materials.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Mining locations for fissionable source... MINERAL DEVELOPMENT Fissionable Source Materials § 3746.1 Mining locations for fissionable source... (68 Stat. 921), it is clear that after enactment of said Act of August 13, 1954, valid...

  7. 43 CFR 3746.1 - Mining locations for fissionable source materials.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Mining locations for fissionable source... MINERAL DEVELOPMENT Fissionable Source Materials § 3746.1 Mining locations for fissionable source... (68 Stat. 921), it is clear that after enactment of said Act of August 13, 1954, valid...

  8. PyVCI: A flexible open-source code for calculating accurate molecular infrared spectra

    NASA Astrophysics Data System (ADS)

    Sibaev, Marat; Crittenden, Deborah L.

    2016-06-01

    The PyVCI program package is a general purpose open-source code for simulating accurate molecular spectra, based upon force field expansions of the potential energy surface in normal mode coordinates. It includes harmonic normal coordinate analysis and vibrational configuration interaction (VCI) algorithms, implemented primarily in Python for accessibility but with time-consuming routines written in C. Coriolis coupling terms may be optionally included in the vibrational Hamiltonian. Non-negligible VCI matrix elements are stored in sparse matrix format to alleviate the diagonalization problem. CPU and memory requirements may be further controlled by algorithmic choices and/or numerical screening procedures, and recommended values are established by benchmarking using a test set of 44 molecules for which accurate analytical potential energy surfaces are available. Force fields in normal mode coordinates are obtained from the PyPES library of high quality analytical potential energy surfaces (to 6th order) or by numerical differentiation of analytic second derivatives generated using the GAMESS quantum chemical program package (to 4th order).

  9. Poynting-vector based method for determining the bearing and location of electromagnetic sources

    DOEpatents

    Simons, David J.; Carrigan, Charles R.; Harben, Philip E.; Kirkendall, Barry A.; Schultz, Craig A.

    2008-10-21

    A method and apparatus is utilized to determine the bearing and/or location of sources, such as, alternating current (A.C.) generators and loads, power lines, transformers and/or radio-frequency (RF) transmitters, emitting electromagnetic-wave energy for which a Poynting-Vector can be defined. When both a source and field sensors (electric and magnetic) are static, a bearing to the electromagnetic source can be obtained. If a single set of electric (E) and magnetic (B) sensors are in motion, multiple measurements permit location of the source. The method can be extended to networks of sensors allowing determination of the location of both stationary and moving sources.

  10. PC-based real-time acoustic source locator and sound capture system for teleconferencing

    NASA Astrophysics Data System (ADS)

    Morde, Ashutosh; Grove, Deborah; Utama, Robert

    2002-05-01

    A PC-based real time acoustic source locator and sound capture system has been developed. The system is implemented using Frontier Design A/D converters and the Intel Signal Processing Library directly on a 1 GHz Pentium III machine, without a DSP board. The source locator uses the cross-power spectral phase to locate a moving talker. The algorithm also uses an energy detector that minimizes incorrect location estimates by neglecting frames with high background noise. The source locator provides 8 location estimates per second. A 16-element 0.90 m linear delay-sum beamformer has also been implemented in the system as a method for selective sound capture. The ability of the source locator to detect talkers in a typical office environment is evaluated. In addition, the array response is measured. [Work supported by Intel.

  11. Fast, Accurate and Precise Mid-Sagittal Plane Location in 3D MR Images of the Brain

    NASA Astrophysics Data System (ADS)

    Bergo, Felipe P. G.; Falcão, Alexandre X.; Yasuda, Clarissa L.; Ruppert, Guilherme C. S.

    Extraction of the mid-sagittal plane (MSP) is a key step for brain image registration and asymmetry analysis. We present a fast MSP extraction method for 3D MR images, based on automatic segmentation of the brain and on heuristic maximization of the cerebro-spinal fluid within the MSP. The method is robust to severe anatomical asymmetries between the hemispheres, caused by surgical procedures and lesions. The method is also accurate with respect to MSP delineations done by a specialist. The method was evaluated on 64 MR images (36 pathological, 20 healthy, 8 synthetic), and it found a precise and accurate approximation of the MSP in all of them with a mean time of 60.0 seconds per image, mean angular variation within a same image (precision) of 1.26o and mean angular difference from specialist delineations (accuracy) of 1.64o.

  12. A simplified approach to characterizing a kilovoltage source spectrum for accurate dose computation

    SciTech Connect

    Poirier, Yannick; Kouznetsov, Alexei; Tambasco, Mauro

    2012-06-15

    % for the homogeneous and heterogeneous block phantoms, and agreement for the transverse dose profiles was within 6%. Conclusions: The HVL and kVp are sufficient for characterizing a kV x-ray source spectrum for accurate dose computation. As these parameters can be easily and accurately measured, they provide for a clinically feasible approach to characterizing a kV energy spectrum to be used for patient specific x-ray dose computations. Furthermore, these results provide experimental validation of our novel hybrid dose computation algorithm.

  13. 43 CFR 3746.1 - Mining locations for fissionable source materials.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... locations under the mining laws of the United States may be based upon a discovery of a mineral deposit..., heretofore located under the mining laws of the United States for or based upon a discovery of a mineral... MINERAL DEVELOPMENT Fissionable Source Materials § 3746.1 Mining locations for fissionable...

  14. 43 CFR 3746.1 - Mining locations for fissionable source materials.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... locations under the mining laws of the United States may be based upon a discovery of a mineral deposit..., heretofore located under the mining laws of the United States for or based upon a discovery of a mineral... MINERAL DEVELOPMENT Fissionable Source Materials § 3746.1 Mining locations for fissionable...

  15. Rapid estimation of tsunami source centroid location using a dense offshore observation network

    NASA Astrophysics Data System (ADS)

    Yamamoto, N.; Hirata, K.; Aoi, S.; Suzuki, W.; Nakamura, H.; Kunugi, T.

    2016-05-01

    This paper proposes a rapid method of estimating tsunami source locations using real-time ocean-bottom hydrostatic pressure data from a dense offshore observation network. We defined two characteristic locations representing the real-time tsunami disturbance and the initial sea surface height distribution. First, we defined the tsunami centroid location (TCL), which is the centroid location of the maximum absolute amplitude of the real-time ocean-bottom hydrostatic pressure changes. Second, we defined the centroid location of the absolute values of the initial sea surface height displacements. To determine whether the TCL can approximate the centroid location of the tsunami source, we examined approximately 1000 near-field synthetic tsunami scenarios and a realistic tsunami scenario of the 2011 Tohoku earthquake in the Japan Trench. From these examinations, it was confirmed that in most scenarios, the TCLs obtained within a few minutes after the occurrence of an earthquake were close to the actual corresponding tsunami source locations.

  16. One dimensional P wave velocity structure of the crust beneath west Java and accurate hypocentre locations from local earthquake inversion

    SciTech Connect

    Supardiyono; Santosa, Bagus Jaya

    2012-06-20

    A one-dimensional (1-D) velocity model and station corrections for the West Java zone were computed by inverting P-wave arrival times recorded on a local seismic network of 14 stations. A total of 61 local events with a minimum of 6 P-phases, rms 0.56 s and a maximum gap of 299 Degree-Sign were selected. Comparison with previous earthquake locations shows an improvement for the relocated earthquakes. Tests were carried out to verify the robustness of inversion results in order to corroborate the conclusions drawn out from our reasearch. The obtained minimum 1-D velocity model can be used to improve routine earthquake locations and represents a further step toward more detailed seismotectonic studies in this area of West Java.

  17. Swift Gamma-Ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bundas, David J.

    2004-01-01

    The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up narrow field instruments capable of multi-wavelength (UV, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space- based observatories drive the end-to-end data analysis and distribution requirements. The Swift mission is managed by the GSFC, and includes an international team of contributors that each bring their unique perspective that have proven invaluable to the mission. The spacecraft bus, provided by Spectrum Astro, Inc. was procured through a Rapid Spacecraft Development Office (RSDO) contract by the GSFC. There are three instruments: the Burst Alert Telescope (BAT) provided by the GSFC; the X-Ray Telescope (XRT) provided by a team led by the Pennsylvania State University (PSU); and the Ultra-Violet Optical Telescope (UVOT), again managed by PSU. The Mission Operations Center (MOC) was developed by and is located at PSU. Science archiving and data analysis centers are located at the GSFC, in the UK and in Italy.

  18. Helicopter Based Magnetic Detection Of Wells At The Teapot Dome (Naval Petroleum Reserve No. 3 Oilfield: Rapid And Accurate Geophysical Algorithms For Locating Wells

    NASA Astrophysics Data System (ADS)

    Harbert, W.; Hammack, R.; Veloski, G.; Hodge, G.

    2011-12-01

    In this study Airborne magnetic data was collected by Fugro Airborne Surveys from a helicopter platform (Figure 1) using the Midas II system over the 39 km2 NPR3 (Naval Petroleum Reserve No. 3) oilfield in east-central Wyoming. The Midas II system employs two Scintrex CS-2 cesium vapor magnetometers on opposite ends of a transversely mounted, 13.4-m long horizontal boom located amidships (Fig. 1). Each magnetic sensor had an in-flight sensitivity of 0.01 nT. Real time compensation of the magnetic data for magnetic noise induced by maneuvering of the aircraft was accomplished using two fluxgate magnetometers mounted just inboard of the cesium sensors. The total area surveyed was 40.5 km2 (NPR3) near Casper, Wyoming. The purpose of the survey was to accurately locate wells that had been drilled there during more than 90 years of continuous oilfield operation. The survey was conducted at low altitude and with closely spaced flight lines to improve the detection of wells with weak magnetic response and to increase the resolution of closely spaced wells. The survey was in preparation for a planned CO2 flood to enhance oil recovery, which requires a complete well inventory with accurate locations for all existing wells. The magnetic survey was intended to locate wells that are missing from the well database and to provide accurate locations for all wells. The well location method used combined an input dataset (for example, leveled total magnetic field reduced to the pole), combined with first and second horizontal spatial derivatives of this input dataset, which were then analyzed using focal statistics and finally combined using a fuzzy combination operation. Analytic signal and the Shi and Butt (2004) ZS attribute were also analyzed using this algorithm. A parameter could be adjusted to determine sensitivity. Depending on the input dataset 88% to 100% of the wells were located, with typical values being 95% to 99% for the NPR3 field site.

  19. Optical identifications of radio sources with accurate positions using the United Kingdom Schmidt Telescope (UKST) IIIa-J plates

    NASA Technical Reports Server (NTRS)

    Savage, A.

    1986-01-01

    Several programs are making use of UKST Sky Survey plates to identify southern radio sources. The fine-grain modern plates and accurate radio positions give a much improved identification rate. It seems that it will very soon be possible to determine whether or not there is a quasar redshift cut-off at z of about 4. There is an urgent need for more accurate fundamental reference star positions in the South.

  20. Swift Gamma-ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bundas, David J.

    2005-01-01

    The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up with narrow field instruments capable of multi-wavelength (UT, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space-based observatories drive the end-to-end data analysis and distribution requirements.

  1. Swift Gamma-Ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bundas, David J.

    2004-01-01

    The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up with narrow field instruments capable of multi-wavelength (UV, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space-based observatories drive the end-to-end data analysis and distribution requirements.

  2. Determination of Jet Noise Radiation Source Locations using a Dual Sideline Cross-Correlation/Spectrum Technique

    NASA Technical Reports Server (NTRS)

    Allen, C. S.; Jaeger, S. M.

    1999-01-01

    The goal of our efforts is to extrapolate nearfield jet noise measurements to the geometric far field where the jet noise sources appear to radiate from a single point. To accomplish this, information about the location of noise sources in the jet plume, the radiation patterns of the noise sources and the sound pressure level distribution of the radiated field must be obtained. Since source locations and radiation patterns can not be found with simple single microphone measurements, a more complicated method must be used.

  3. Seismic monitoring of EGS tests at the Coso Geothermal area, California, using accurate MEQ locations and full moment tensors

    SciTech Connect

    Foulger, G.R.; B.R. Julian, B.R.; F. Monastero

    2008-04-01

    We studied high-resolution relative locations and full moment tensors of microearthquakes (MEQs) occurring before, during and following Enhanced Geothermal Systems (EGS) experiments in two wells at the Coso geothermal area, California. The objective was to map new fractures, determine the mode and sense of failure, and characterize the stress cycle associated with injection. New software developed for this work combines waveform crosscorrelation measurement of arrival times with relative relocation methods, and assesses confidence regions for moment tensors derived using linearprogramming methods. For moment tensor determination we also developed a convenient Graphical User Interface (GUI), to streamline the work. We used data from the U.S. Navy’s permanent network of three-component digital borehole seismometers and from 14 portable three-component digital instruments. The latter supplemented the permanent network during injection experiments in well 34A-9 in 2004 and well 34-9RD2 in 2005. In the experiment in well 34A-9, the co-injection earthquakes were more numerous, smaller, more explosive and had more horizontal motion, compared with the pre-injection earthquakes. In the experiment in well 34-9RD2 the relocated hypocenters reveal a well-defined planar structure, 700 m long and 600 m high in the depth range 0.8 to 1.4 km below sea level, striking N 20° E and dipping at 75° to the WNW. The moment tensors show that it corresponds to a mode I (opening) crack. For both wells, the perturbed stress state near the bottom of the well persisted for at least two months following the injection.

  4. Determination of Jet Noise Radiation Patterns and Source Locations using 2-Dimensional Intensity Measurements

    NASA Technical Reports Server (NTRS)

    Jaeger, S. M.; Allen, C. S.

    1999-01-01

    Contents include the following: (1) Outline Jet Noise extrapolation to far field. (2) Two dimensional sound intensity. (3) Anechoic chamber cold jet test. (4) Results: Intensity levels. Vector maps. Source location centroids. Directivity. and (5) Conclusions.

  5. Detection and Location of Gamma-Ray Sources with a Modulating Coded Mask

    SciTech Connect

    Anderson, Dale N.; Stromswold, David C.; Wunschel, Sharon C.; Peurrung, Anthony J.; Hansen, Randy R.

    2006-01-31

    This paper presents methods of detecting and locating a concelaed nuclear gamma-ray source with a coded aperture mask. Energetic gamma rays readily penetrate moderate amounts of shielding material and can be detected at distances of many meters. The detection of high energy gamma-ray sources is vitally important to national security for several reasons, including nuclear materials smuggling interdiction, monitoring weapon components under treaties, and locating nuclear weapons and materials in the possession terrorist organizations.

  6. Acoustic Emission Source Location Using a Distributed Feedback Fiber Laser Rosette

    PubMed Central

    Huang, Wenzhu; Zhang, Wentao; Li, Fang

    2013-01-01

    This paper proposes an approach for acoustic emission (AE) source localization in a large marble stone using distributed feedback (DFB) fiber lasers. The aim of this study is to detect damage in structures such as those found in civil applications. The directional sensitivity of DFB fiber laser is investigated by calculating location coefficient using a method of digital signal analysis. In this, autocorrelation is used to extract the location coefficient from the periodic AE signal and wavelet packet energy is calculated to get the location coefficient of a burst AE source. Normalization is processed to eliminate the influence of distance and intensity of AE source. Then a new location algorithm based on the location coefficient is presented and tested to determine the location of AE source using a Delta (Δ) DFB fiber laser rosette configuration. The advantage of the proposed algorithm over the traditional methods based on fiber Bragg Grating (FBG) include the capability of: having higher strain resolution for AE detection and taking into account two different types of AE source for location. PMID:24141266

  7. Identification of contaminant point source in surface waters based on backward location probability density function method

    NASA Astrophysics Data System (ADS)

    Cheng, Wei Ping; Jia, Yafei

    2010-04-01

    A backward location probability density function (BL-PDF) method capable of identifying location of point sources in surface waters is presented in this paper. The relation of forward location probability density function (FL-PDF) and backward location probability density, based on adjoint analysis, is validated using depth-averaged free-surface flow and mass transport models and several surface water test cases. The solutions of the backward location PDF transport equation agreed well to the forward location PDF computed using the pollutant concentration at the monitoring points. Using this relation and the distribution of the concentration detected at the monitoring points, an effective point source identification method is established. The numerical error of the backward location PDF simulation is found to be sensitive to the irregularity of the computational meshes, diffusivity, and velocity gradients. The performance of identification method is evaluated regarding the random error and number of observed values. In addition to hypothetical cases, a real case was studied to identify the source location where a dye tracer was instantaneously injected into a stream. The study indicated the proposed source identification method is effective, robust, and quite efficient in surface waters; the number of advection-diffusion equations needed to solve is equal to the number of observations.

  8. An efficient closed-form solution for acoustic emission source location in three-dimensional structures

    SciTech Connect

    Li, Xibing; Dong, Longjun

    2014-02-15

    This paper presents an efficient closed-form solution (ECS) for acoustic emission(AE) source location in three-dimensional structures using time difference of arrival (TDOA) measurements from N receivers, N ≥ 6. The nonlinear location equations of TDOA are simplified to linear equations. The unique analytical solution of AE sources for unknown velocity system is obtained by solving the linear equations. The proposed ECS method successfully solved the problems of location errors resulting from measured deviations of velocity as well as the existence and multiplicity of solutions induced by calculations of square roots in existed close-form methods.

  9. Locating and quantifying gas emission sources using remotely obtained concentration data

    NASA Astrophysics Data System (ADS)

    Hirst, Bill; Jonathan, Philip; González del Cueto, Fernando; Randell, David; Kosut, Oliver

    2013-08-01

    We describe a method for detecting, locating and quantifying sources of gas emissions to the atmosphere using remotely obtained gas concentration data; the method is applicable to gases of environmental concern. We demonstrate its performance using methane data collected from aircraft. Atmospheric point concentration measurements are modelled as the sum of a spatially and temporally smooth atmospheric background concentration, augmented by concentrations due to local sources. We model source emission rates with a Gaussian mixture model and use a Markov random field to represent the atmospheric background concentration component of the measurements. A Gaussian plume atmospheric eddy dispersion model represents gas dispersion between sources and measurement locations. Initial point estimates of background concentrations and source emission rates are obtained using mixed ℓ2 - ℓ1 optimisation over a discretised grid of potential source locations. Subsequent reversible jump Markov chain Monte Carlo inference provides estimated values and uncertainties for the number, emission rates and locations of sources unconstrained by a grid. Source area, atmospheric background concentrations and other model parameters, including plume model spreading and Lagrangian turbulence time scale, are also estimated. We investigate the performance of the approach first using a synthetic problem, then apply the method to real airborne data from a 1600 km2 area containing two landfills, then a 225 km2 area containing a gas flare stack.

  10. Effective AE source location of damages in the wind turbine blade

    NASA Astrophysics Data System (ADS)

    Yoon, D. J.; Han, B. H.

    2012-05-01

    Acoustic emission (AE) has emerged as a powerful nondestructive tool to detect preexisting defects or to characterize failure mechanisms. Recently, this technique or this kind of principle, that is an in-situ monitoring of inside damages of materials or structures, becomes increasingly popular for monitoring the integrity of large structures like a huge wind blade. Therefore, it is required to find a symptom of damage propagation before catastrophic failure through a continuous monitoring. In this study, we have tried to develop a source location algorithm for damage identification on the part of real wind turbine blade. First, it was focused to understand the activities of acoustic emission events generated from the glass fiber reinforced plastic (GFRP) structures such as a wind blade. Secondly, this study aims to identify and locate the damages from blade specimens. In this work, the activities of AE signals generated from external artificial sources was evaluated and located by new developed source location algorithm. The results show that new suggested source location algorithm was much higher performance than conventional source location method.

  11. Network-based evaluation of infrasound source location at Sakurajima Volcano, Japan

    NASA Astrophysics Data System (ADS)

    McKee, K. F.; Fee, D.; Rowell, C. R.; Johnson, J. B.; Yokoo, A.; Matoza, R. S.

    2013-12-01

    An important step in advancing the science and application of volcano infrasound is improved source location and characterization. Here we evaluate different network-based infrasonic source location methods, primarily srcLoc and semblance, using data collected at Sakurajima Volcano, Japan in July 2013. We investigate these methods in 2- and 3-dimensions to assess the necessity of considering 3-D sensor and vent locations. In addition, we compare source locations found using array back azimuth projection from dual arrays. The effect of significant local topography on source location will also be evaluated. Preliminary analysis indicates periods of high- and low-level activity, suggesting different processes occurring in the upper conduit and vent. Network processing will be applied to determine signal versus noise, a technique which illuminates when the volcano is producing infrasound, to further investigate these processes. We combine this with other methods to identify the number and style of eruptions. By bringing together source location, timing of activity level, type of activity (such as tremor, explosions, etc.), and number of events, we aim to improve understanding of the activity and associated infrasound signals at Sakurajima Volcano.

  12. Effective dose equivalent for point gamma sources located 10 cm near the body.

    PubMed

    Xu, X George; Bushart, Sean; Anderson, Ralph

    2006-08-01

    The key component in the so-called EPRI effective dose equivalent (EDE) methodology is an algorithm that utilizes two dosimeters (instead of multiple dosimeters) to predict the EDE for external photon exposures. The exposure scenarios that were previously studied in deriving the algorithm include parallel photon beams and point sources 33 cm from the body surface. The motivation for this study was the need to investigate source locations within 33 cm from the body so the method is more widely applicable. The ORNL stylized mathematical human phantoms and the MCNP code were used to calculate organ doses in this study. This paper presents the EDE data for point gamma sources at 0.3, 1.0, and 1.5 MeV, respectively, which are located at 10 cm from the surface of the body. The results and analyses show that the locations ranging from the overhead to the foot have resulted in conservative ratios except for two general regions near the front upper thigh and directly overhead. If all locations considered in this study were averaged for each photon energy, the overall ratio is on the conservative side. These data suggest that the EPRI EDE methodology is still valid for sources located 10 cm from the body, although the chance for resulting in a non-conservative estimate of the EDE has increased in comparison with the sources located at 30 cm from the body. Finally, this paper provides recommendations on how to apply the EPRI EDE methodology. PMID:16832191

  13. Macro-fiber composite piezoelectric rosettes for acoustic source location in complex structures

    NASA Astrophysics Data System (ADS)

    Matt, Howard; Lanza di Scalea, Francesco

    2007-04-01

    An approach based upon the employment of piezoelectric transducer rosettes is proposed for passive damage or impact location in anisotropic or geometrically-complex structures. The rosettes are comprised of rectangular Macro-Fiber Composite (MFC) transducers which exhibit a highly directive response to ultrasonic guided waves. The MFC response to flexural (A 0) motion is decomposed into axial and transverse sensitivity factors, which allow extraction of the direction of an incoming wave using rosette principles. The wave source location in a plane is then simply determined by intersecting the wave directions detected by two rosettes. The rosette approach is applicable to anisotropic or geometrically-complex structures where conventional time-of-flight source location is challenging due to the direction-dependent wave velocity. The performance of the rosettes for source location is validated through pencil-lead breaks performed on an aluminum plate, an anisotropic CFRP laminate, and a complex CFRP-honeycomb sandwich panel.

  14. Correlation of Earthquake Locations with Volumetric Source Components in TauTona Gold Mine, South Africa

    NASA Astrophysics Data System (ADS)

    Kane, D. L.; Boettcher, M. S.

    2013-12-01

    We investigate the source characteristics of earthquakes in TauTona Gold Mine, South Africa, to test if the location of earthquakes relative to mining structures is correlated with significant isotropic source behavior. Earthquakes are well monitored in TauTona Mine, where underground near-source stations record smaller events and higher frequency energy than can generally be observed using surface stations. Our dataset includes -4 < Mw < 4 earthquakes recorded at hypocentral distances of tens of meters to a few kilometers. The locations of structures in the mine, including faults, dikes, tunnels, and stopes, are well known from detailed geologic mapping and surveyed mine plans. We use data collected between 2004 and 2009 from the in-mine array (1-6 kHz), the Natural Earthquake Laboratory in South African Mines (NELSAM) project stations (6-12 kHz), and a short-term PASSCAL experiment (200 Hz) to study source mechanism variability and correlation with mapped structures within the mine. Previous studies of earthquakes in mines suggest a relationship between earthquake size and isotropic moment tensor source characteristics. In TauTona Mine, earthquakes with significant implosive source characteristics tend to be infrequent, larger events (Mw > 1.5), whereas earthquakes with significant explosive source characteristics tend to be smaller (Mw < 0). A possible model for this variability in source behavior relates earthquake size to earthquake location relative to mining and natural structures. Larger events are more likely to produce closure of tunnels and stopes within the mine, whereas the smallest recorded explosive events can be interpreted as opening cracks that form at the edges of mining structures. Double-couple type sources occur throughout the full magnitude range, and are often located along mapped faults and dikes. We focus our analysis on earthquakes located near the NELSAM stations in the deepest part of the mine, and on earthquakes located at depths

  15. Source location of the smooth high-frequency radio emissions from Uranus

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Calvert, W.

    1989-01-01

    The source location of the smooth high-frequency radio emissions from Uranus has been determined. Specifically, by fitting the signal dropouts which occurred as Voyager traversed the hollow center of the emission pattern to a symmetrical cone centered on the source magnetic field direction at the cyclotron frequency, a southern-hemisphere (nightside) source was found at approximately 56 deg S, 219 deg W. The half-angle for the hollow portion of the emission pattern was found to be 13 deg.

  16. Precise source location of the anomalous 1979 March 5 gamma ray transient

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Teegarden, B. J.; Evans, W. D.; Klebesadel, R. W.; Laros, J. G.; Barat, C.; Hurley, K.; Niel, M.; Vedrenne, G.

    1981-01-01

    Refinements in the source direction analysis of the observations of the unusual gamma ray transient are presented. The final results from the interplanetary gamma ray burst network produce a 0.1 arc sq. min. error box. It is nested inside the initially determined 2 arc sq min. source region. This smaller source location is within both the optical and X-ray contours of N49 although not positioned at either contour center.

  17. Bayesian statistics applied to the location of the source of explosions at Stromboli Volcano, Italy

    USGS Publications Warehouse

    Saccorotti, G.; Chouet, B.; Martini, M.; Scarpa, R.

    1998-01-01

    We present a method for determining the location and spatial extent of the source of explosions at Stromboli Volcano, Italy, based on a Bayesian inversion of the slowness vector derived from frequency-slowness analyses of array data. The method searches for source locations that minimize the error between the expected and observed slowness vectors. For a given set of model parameters, the conditional probability density function of slowness vectors is approximated by a Gaussian distribution of expected errors. The method is tested with synthetics using a five-layer velocity model derived for the north flank of Stromboli and a smoothed velocity model derived from a power-law approximation of the layered structure. Application to data from Stromboli allows for a detailed examination of uncertainties in source location due to experimental errors and incomplete knowledge of the Earth model. Although the solutions are not constrained in the radial direction, excellent resolution is achieved in both transverse and depth directions. Under the assumption that the horizontal extent of the source does not exceed the crater dimension, the 90% confidence region in the estimate of the explosive source location corresponds to a small volume extending from a depth of about 100 m to a maximum depth of about 300 m beneath the active vents, with a maximum likelihood source region located in the 120- to 180-m-depth interval.

  18. Location and release time identification of pollution point source in river networks based on the Backward Probability Method.

    PubMed

    Ghane, Alireza; Mazaheri, Mehdi; Mohammad Vali Samani, Jamal

    2016-09-15

    The pollution of rivers due to accidental spills is a major threat to environment and human health. To protect river systems from accidental spills, it is essential to introduce a reliable tool for identification process. Backward Probability Method (BPM) is one of the most recommended tools that is able to introduce information related to the prior location and the release time of the pollution. This method was originally developed and employed in groundwater pollution source identification problems. One of the objectives of this study is to apply this method in identifying the pollution source location and release time in surface waters, mainly in rivers. To accomplish this task, a numerical model is developed based on the adjoint analysis. Then the developed model is verified using analytical solution and some real data. The second objective of this study is to extend the method to pollution source identification in river networks. In this regard, a hypothetical test case is considered. In the later simulations, all of the suspected points are identified, using only one backward simulation. The results demonstrated that all suspected points, determined by the BPM could be a possible pollution source. The proposed approach is accurate and computationally efficient and does not need any simplification in river geometry and flow. Due to this simplicity, it is highly recommended for practical purposes. PMID:27219462

  19. An analytic method to determine the effect of source modeling errors on the apparent location and direction of biological sources

    NASA Astrophysics Data System (ADS)

    de Munck, J. C.; van Dijk, B. W.; Spekreijse, H.

    1988-02-01

    Evoked potentials (EPs) and electroencephalograms (EEGs) can be used to determine the location, the direction, and strength of electrical brain activity. For this purpose mathematical models are used which describe regions in the head with different conductivity. In most models, the sources are described by mathematical (current) point dipoles. However, EPs and EEGs are generated with more extensive cortical areas. In this study an analytic method is described to calculate the effect of source extension on the potential distribution measured at the scalp and also on the difference between the location of the extended source and the location of the equivalent point dipole. General formulas are derived which express in spherical harmonics the potential distribution that results from a circularly symmetric extended source. It is shown that for sources that obey specific symmetries the influence of source extension on the potential distribution is a fourth-order effect in the distance between electrode and the origin (the middle point of the head), and a second-order effect in the extension. It is also shown that for such sources the error in localization (i.e., the distance between the position of the equivalent dipole and the center of the extended source) is zero when Geselowitz's method [IEEE Trans. Biomed. Eng. BME-12, 164 (1965)] is used. Because in volume conductor models the relation between source and potential is given by Poisson's equation, it is suggested by the authors that the results of the present study may be extended to applications in other fields of physics as well.

  20. Improved centroid moment tensor analyses in the NIED AQUA (Accurate and QUick Analysis system for source parameters)

    NASA Astrophysics Data System (ADS)

    Kimura, H.; Asano, Y.; Matsumoto, T.

    2012-12-01

    The rapid determination of hypocentral parameters and their transmission to the public are valuable components of disaster mitigation. We have operated an automatic system for this purpose—termed the Accurate and QUick Analysis system for source parameters (AQUA)—since 2005 (Matsumura et al., 2006). In this system, the initial hypocenter, the moment tensor (MT), and the centroid moment tensor (CMT) solutions are automatically determined and posted on the NIED Hi-net Web site (www.hinet.bosai.go.jp). This paper describes improvements made to the AQUA to overcome limitations that became apparent after the 2011 Tohoku Earthquake (05:46:17, March 11, 2011 in UTC). The improvements included the processing of NIED F-net velocity-type strong motion records, because NIED F-net broadband seismographs are saturated for great earthquakes such as the 2011 Tohoku Earthquake. These velocity-type strong motion seismographs provide unsaturated records not only for the 2011 Tohoku Earthquake, but also for recording stations located close to the epicenters of M>7 earthquakes. We used 0.005-0.020 Hz records for M>7.5 earthquakes, in contrast to the 0.01-0.05 Hz records employed in the original system. The initial hypocenters determined based on arrival times picked by using seismograms recorded by NIED Hi-net stations can have large errors in terms of magnitude and hypocenter location, especially for great earthquakes or earthquakes located far from the onland Hi-net network. The size of the 2011 Tohoku Earthquake was initially underestimated in the AQUA to be around M5 at the initial stage of rupture. Numerous aftershocks occurred at the outer rise east of the Japan trench, where a great earthquake is anticipated to occur. Hence, we modified the system to repeat the MT analyses assuming a larger size, for all earthquakes for which the magnitude was initially underestimated. We also broadened the search range of centroid depth for earthquakes located far from the onland Hi

  1. Descent of tremor source locations before the 2014 phreatic eruption of Ontake volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ogiso, Masashi; Matsubayashi, Hirotoshi; Yamamoto, Tetsuya

    2015-12-01

    On 27 September 2014, Ontake volcano, in central Japan, suddenly erupted without precursory activity. We estimated and tracked the source locations of volcanic tremor associated with the eruption at high temporal resolution, using a method based on the spatial distribution of tremor amplitudes. Although the tremor source locations were not well constrained in depth, their epicenters were well located beneath the erupted crater and the summit. Tremor sources were seen to descend approximately 2 km over a period of several minutes prior to the beginning of the eruption. Detailed analysis of the time series of tremor amplitudes suggests that this descent is a robust feature. Our finding may be an important constraint for modeling the 2014 eruption of Ontake volcano as well as for monitoring activities on this and other volcanoes.

  2. Characterization of Source and Wave Propagation Effects of Volcano-seismic Events and Tremor Using the Amplitude Source Location Method

    NASA Astrophysics Data System (ADS)

    Kumagai, H.; Londono, J. M.; López, C. M.; Ruiz, M. C.; Mothes, P. A.; Maeda, Y.

    2015-12-01

    We propose application of the amplitude source location (ASL) method to characterize source and wave propagation effects of volcano-seismic events and tremor observed at different volcanoes. We used this method to estimate the source location and source amplitude from high-frequency (5-10 Hz) seismic amplitudes under the assumption of isotropic S-wave radiation. We estimated the cumulative source amplitude (Is) as the offset value of the time-integrated envelope of the vertical seismogram corrected for geometrical spreading and medium attenuation in the 5-10 Hz band. We studied these parameters of tremor signals associated with eruptions and explosion events at Tungurahua volcano, Ecuador; long-period (LP) events at Cotopaxi volcano, Ecuador; and LP events at Nevado del Ruiz volcano, Colombia. We identified two types of eruption tremor at Tungurahua; noise-like inharmonic waveforms and harmonic oscillatory signals. We found that Is increased linearly with increasing source amplitude for explosion events and LP events, and that Is increased exponentially with increasing source amplitude for inharmonic eruption tremor signals. The source characteristics of harmonic eruption tremor signals differed from those of inharmonic tremor signals. The Is values we estimated for inharmonic eruption tremor were consistent with previous estimates of volumes of tephra fallout. The linear relationship between the source amplitude and Is for LP events can be explained by the wave propagation effects in the diffusion model for multiple scattering assuming a diffusion coefficient of 105 m2/s and an intrinsic Q factor of around 50. The resultant mean free path is approximately 100 m. Our results suggest that Cotopaxi and Nevado del Ruiz volcanoes have similar highly scattering and attenuating structures. Our approach provides a systematic way to compare the size of volcano-seismic signals observed at different volcanoes. The scaling relations among source parameters that we identified

  3. Surface Properties Associated With Dust Storm Plume's Point-Source Locations In The Border Region Of The US And Mexico

    NASA Astrophysics Data System (ADS)

    Bleiweiss, M. P.; DuBois, D. W.; Flores, M. I.

    2013-12-01

    Dust storms in the border region of the Southwest US and Northern Mexico are a serious problem for air quality (PM10 exceedances), health (Valley Fever is pandemic in the region) and transportation (road closures and deadly traffic accidents). In order to better understand the phenomena, we are attempting to identify critical characteristics of dust storm sources so that, possibly, one can perform more accurate predictions of events and, thus, mitigate some of the deleterious effects. Besides the emission mechanisms for dust storm production that are tied to atmospheric dynamics, one must know those locations whose source characteristics can be tied to dust production and, therefore, identify locations where a dust storm is eminent under favorable atmospheric dynamics. During the past 13 years, we have observed, on satellite imagery, more than 500 dust events in the region and are in the process of identifying the source regions for the dust plumes that make up an event. Where satellite imagery exists with high spatial resolution (less than or equal to 250m), dust 'plumes' appear to be made up of individual and merged plumes that are emitted from a 'point source' (smaller than the resolution of the imagery). In particular, we have observed events from the ASTER sensor whose spatial resolution is 15m as well as Landsat whose spatial resolution is 30m. Tying these source locations to surface properties such as NDVI, albedo, and soil properties (percent sand, silt, clay, and gravel; soil moisture; etc.) will identify regions with enhanced capability to produce a dust storm. This, along with atmospheric dynamics, will allow the forecast of dust events. The analysis of 10 events from the period 2004-2013, for which we have identified 1124 individual plumes, will be presented.

  4. Quantification of Methane Source Locations and Emissions in AN Urban Setting

    NASA Astrophysics Data System (ADS)

    Crosson, E.; Richardson, S.; Tan, S. M.; Whetstone, J.; Bova, T.; Prasad, K. R.; Davis, K. J.; Phillips, N. G.; Turnbull, J. C.; Shepson, P. B.; Cambaliza, M. L.

    2011-12-01

    The regulation of methane emissions from urban sources such as landfills and waste-water treatment facilities is currently a highly debated topic in the US and in Europe. This interest is fueled, in part, by recent measurements indicating that urban emissions are a significant source of Methane (CH4) and in fact may be substantially higher than current inventory estimates(1). As a result, developing methods for locating and quantifying emissions from urban methane sources is of great interest to industries such as landfill and wastewater treatment facility owners, watchdog groups, and the governmental agencies seeking to evaluate or enforce regulations. In an attempt to identify major methane source locations and emissions in Boston, Indianapolis, and the Bay Area, systematic measurements of CH4 concentrations and meteorology data were made at street level using a vehicle mounted cavity ringdown analyzer. A number of discrete sources were detected at concentration levels in excess of 15 times background levels. Using Gaussian plume models as well as tomographic techniques, methane source locations and emission rates will be presented. In addition, flux chamber measurements of discrete sources such as those found in natural gas leaks will also be presented. (1) Wunch, D., P.O. Wennberg, G.C. Toon, G. Keppel-Aleks, and Y.G. Yavin, Emissions of Greenhouse Gases from a North American Megacity, Geophysical Research Letters, Vol. 36, L15810, doi:10.1029/2009GL)39825, 2009.

  5. Accounting for uncertainty in location when detecting point sources using infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Nichols, J. M.; Waterman, J. R.

    2016-07-01

    This work derives the modeling and detection theory required to predict the performance of an infrared focal plane array in detecting point source targets. Specifically, we focus on modeling the uncertainty associated with the location of the point source on the array. In the process we derive several new expressions related to pixel-averaged detection performance under a variety of problem assumptions. The resulting predictions are compared to standard approaches where the location is assumed fixed and known. It is further shown how to incorporate these predictions into multi-frame detection strategies.

  6. East Asia Dust Source Location Using the Naval Research Laboratory's 1-km Dust Enhancement Product

    NASA Astrophysics Data System (ADS)

    Walker, A. L.; Curtis, C. A.; Miller, S. D.; Richardson, K.; Westphal, D. L.

    2011-12-01

    In the effort to predict dust storms and their effects on local, regional and global scales an often cited uncertainty is the precise location of dust sources. Many approaches have been used to identify major dust source regions in East Asia. These approaches include analysis of station data for frequency of dust storms, drifting dust, dusty day, wind speed, and PM10 total suspended particulates. Some approaches emphasize the location of land surface type (Gobi, sandy desert, and loess) and geomorphological setting/features (basins, plateaus, alluvial fans, dry rivers, or oases). Other approaches use remote sensing to locate areas of high dust activity using the Total Ozone Mapping Spectrometer Aerosol Index (TOMS AI) data, to correlate Normalized Difference Vegetation Index (NDVI) vegetation cover with dust storm frequency, or to track dust storm event origination by analyzing Moderate Resolution Imaging Spectroradiometer (MODIS) images. It is also customary for researchers to combine two or more of these approaches to identify dust source regions. In this paper we use a novel approach to locate dust sources in East Asia. Utilizing the Naval Research Laboratory's satellite derived 1-km Dust Enhancement Product (DEP) imagery we can readily distinguish elevated dust over land from other components of the scene and individual dust plumes are readily seen. The high resolution of the DEP allows the many small, eroding point sources (measuring 1-10s km across) that form individual plumes to be located. Five years (2007 - 2011) of East Asia DEP imagery have been analyzed. Dust source frequency plots will be shown highlighting the most active dust source areas in East Asia. Our results show the most active point sources are located along the slopes and around the rim of large basins. Within basins, on plateaus and in valleys point sources are concentrated in smaller depressions relative to the surrounding topography. Point sources are also associated with the action of

  7. Improvements in mining induced microseismic source locations at the Lucky Friday mine using an automated whole-waveform analysis system

    NASA Astrophysics Data System (ADS)

    Dodge, Douglas A.; Sprenke, Kenneth F.

    1992-09-01

    For years, severe rockburst problems at the Lucky Friday mine in northern Idaho have been a persistent safety hazard and an impediment to production. An MP250 based microseismic monitoring system, which uses simple voltage threshold picking of first arrivals, has been used in this mine since 1973 to provide source locations and energy estimates of seismic events. Recently, interest has been expressed in developing a whole waveform microseismic monitoring system for the mine to provide more accurate source locations and information about source characteristics. For this study, we have developed a prototype whole-waveform microseismic monitoring system based on a 80386 computer equipped with a 50 kHz analog-digital convertor board. The software developed includes a data collection program, a data analysis program, and an event detection program. Whole-waveform data collected and analyzed using this system during a three-day test have been employed to investigate sources of error in the hypocenter location process and to develop an automatic phase picker appropriate for microseismic events. Comparison of hypocenter estimates produced by the MP250 system to those produced by the whole-waveform system shows that significant timing errors are common in the MP250 system and that these errors caused a large part of the scatter evident in the daily activity plots produced at the mine. Simulations and analysis of blast data show that analytical control over the solutions is strongly influenced by the array geometry. Within the geophone array, large errors in the velocity model or moderate timing errors may result in small changes in the solution, but outside the array, the solution is very sensitive to small changes in the data. Our whole-waveform detection program picks event onset times and determines event durations by analysis of a segmented envelope function (SEF) derived from the microseismic signal. The detection program has been tested by comparing its arrival time

  8. Acoustic Emission Source Location in Unidirectional Carbon-Fibre-Reinforced Plastic Plates Using Virtually Trained Artificial Neural Networks

    SciTech Connect

    Caprino, G.; Lopresto, V.; Leone, C.; Papa, I.

    2010-06-02

    Acoustic emission source location in a unidirectional carbon-fibre-reinforced plastic plate was attempted employing Artificial Neural Network (ANN) technology. The acoustic emission events were produced by a lead break, and the response wave received by piezoelectric sensors, type VS150-M resonant at 150 kHz. The waves were detected by a Vallen AMSY4 eight-channel instrumentation. The time of arrival, determined through the conventional threshold crossing technique, was used to measure the dependence of wave velocity on fibre orientation. A simple empirical formula, relying on classical lamination and suggested by wave propagation theory, was able to accurately model the experimental trend. Based on the formula, virtual training and testing data sets were generated for the case of a plate monitored by three transducers, and adopted to select two potentially effective ANN architectures. For final validation, experimental tests were carried out, positioning the source at predetermined points evenly distributed within the plate area. A very satisfactory correlation was found between the actual source locations and the ANN predictions.

  9. Accurate position for the globular cluster X-ray source M15 - 211/X2127 + 119

    NASA Astrophysics Data System (ADS)

    Geffert, M.; Auriere, M.; Ilovaisky, S. A.; Terzan, A.

    1989-01-01

    Two new and improved determinations of the position of the globular cluster X-ray source X2127+119/M15:AC211 are presented. The positions were determined using long focus exposures on CCD frames and photographic and image tube plates. Stars from the SAO and AGK 3 catalogues were taken to derive positions of faint reference stars in the surroundings of the X-ray source. The uncertainty of the best position (in the AGK 3 system) is 0.20 arcsec in alpha and delta. The nominal separation of the optical position and the X-ray position is found to be 2 arcsec, but with an uncertainty of about 1.5 arcsec from the Einstein determination.

  10. Identifying pollutant source directions using multiple analysis methods at a rural location in New York

    NASA Astrophysics Data System (ADS)

    Bae, Min-Suk; Schwab, James J.; Chen, Wei-Nai; Lin, Chuan-Yao; Rattigan, Oliver V.; Demerjian, Kenneth L.

    2011-05-01

    We identify the directionality of sources contributing to observed pollutant concentrations at a rural site through the use of the analysis methods of Conditional Probability Function (CPF) and the Source Direction Probability (SDP). Input data consists of hourly averaged PM 2.5 mass, Organic Mass (OM) from Organic Carbon (OC), optical Elemental Carbon (optical EC), SO 2, CO, NOy, O 3 concentrations and metrological data from Pinnacle State Park site in rural New York State for the period of Dec 2004 to Dec 2008. These measured pollutants are coupled with on-site wind data to identify the directionality of the sources; which are then compared to known stationary source locations from the EPA Air Data web site. Although the CPF plot of the O 3 showed no distinct directionality source area, the Pinnacle State Park site was frequently impacted by plumes of relatively high PM 2.5 mass, SO 2, CO, NOy, optical EC and OM concentrations. Further analysis of the enhanced pollution occurrence frequency from the eastern sector revealed two peaks in the time-of-day distribution of elevated CO, NOy, and optical EC, which provides additional information on the sources. This contrasts with the enhanced pollution occurrence frequency from the south for CO, OM, and optical EC, which shows a single morning peak in its time-of-day distribution and indicates a somewhat more distant, but common source for these carbon-containing pollutants. PM 2.5 mass corresponds to the source areas related to emission facilities listed in the EPA Emissions Inventory, which is further confirmed by correlation and analysis of aerosol optical depth (AOD) data from Moderate-resolution Imaging Spectrometer (MODIS) on board Terra and Aqua satellites. We present evidence that most of the high pollution episodes likely arise from emission sources located several hundred kilometers from the site, indicating mid-long range transport of pollutants to this location.

  11. Locating a compact odor source using a four-channel insect electroantennogram sensor.

    PubMed

    Myrick, A J; Baker, T C

    2011-03-01

    Here we demonstrate the feasibility of using an array of live insects to detect concentrated packets of odor and infer the location of an odor source (∼15 m away) using a backward Lagrangian dispersion model based on the Langevin equation. Bayesian inference allows uncertainty to be quantified, which is useful for robotic planning. The electroantennogram (EAG) is the biopotential developed between the tissue at the tip of an insect antenna and its base, which is due to the massed response of the olfactory receptor neurons to an odor stimulus. The EAG signal can carry tens of bits per second of information with a rise time as short as 12 ms (K A Justice 2005 J. Neurophiol. 93 2233-9). Here, instrumentation including a GPS with a digital compass and an ultrasonic 2D anemometer has been integrated with an EAG odor detection scheme, allowing the location of an odor source to be estimated by collecting data at several downwind locations. Bayesian inference in conjunction with a Lagrangian dispersion model, taking into account detection errors, has been implemented resulting in an estimate of the odor source location within 0.2 m of the actual location. PMID:21160116

  12. Source location of the smooth high-frequency radio emissions from Uranus

    SciTech Connect

    Farrell, W.M.; Calvert, W. )

    1989-05-01

    The source location of the smooth high-frequency (SHF) radio emissions from Uranus has been determined using a technique differing from those applied previously. Specifically, by fitting the signal dropouts which occurred as Voyager traversed the hollow center for the emission pattern to a symmetrical cone centered on the source magnetic field direction at the cyclotron frequency, a southern-hemisphere (nightside) source was found at approximately 56{degree} S, 219{degree} W. The half-angle for the hollow portion of the emission pattern was found to be 13{degree}.

  13. A dual-plane co-RASOR technique for accurate and rapid tracking and position verification of an Ir-192 source for single fraction HDR brachytherapy

    NASA Astrophysics Data System (ADS)

    de Leeuw, Hendrik; Moerland, Marinus A.; van Vulpen, Marco; Seevinck, Peter R.; Bakker, Chris J. G.

    2013-11-01

    Effective high-dose-rate (HDR) treatment requires accurate and independent treatment verification to ensure that the treatment proceeds as prescribed, in particular if a high dose is given, as in single fraction therapy. Contrary to CT imaging and fluoroscopy, MR imaging provides high soft tissue contrast. Conventional MR techniques, however, do not offer the temporal resolution in combination with the 3D spatial resolution required for accurate brachytherapy source localization. We have developed an MR imaging method (center-out RAdial Sampling with Off-Resonance (co-RASOR)) that generates high positive contrast in the geometrical center of field perturbing objects, such as HDR brachytherapy sources. co-RASOR generates high positive contrast in the geometric center of an Ir-192 source by applying a frequency offset to center-out encoded data. To obtain high spatial accuracy in 3D with adequate temporal resolution, two orthogonal center-out encoded 2D images are applied instead of a full 3D acquisition. Its accuracy in 3D is demonstrated by 3D MRI and CT. The 2D images show high positive contrast in the geometric center of non-radioactive Ir-192 sources, with signal intensities up to 160% of the average signal intensity in the surrounding medium. The accuracy with which the center of the Ir-192 source is located by the dual-plane MRI acquisition corresponds closely to the accuracy obtained by 3D MRI and CT imaging. The positive contrast is shown to be obtained in homogeneous and in heterogeneous tissue. The dual-plane MRI technique allows the brachytherapy source to be tracked in 3D with millimeter accuracy with a temporal resolution of approximately 4 s.

  14. Rapid, high-order accurate calculation of flows due to free source or vortex distributions

    NASA Technical Reports Server (NTRS)

    Halsey, D.

    1981-01-01

    Fast Fourier transform (FFT) techniques are applied to the problem of finding the flow due to source or vortex distributions in the field outside an airfoil or other two-dimensional body. Either the complex potential or the complex velocity may be obtained to a high order of accuracy, with computational effort similar to that required by second-order fast Poisson solvers. These techniques are applicable to general flow problems with compressibility and rotation. An example is given of their use for inviscid compressible flow.

  15. Accurate multi-source forest species mapping using the multiple spectral-spatial classification approach

    NASA Astrophysics Data System (ADS)

    Stavrakoudis, Dimitris; Gitas, Ioannis; Karydas, Christos; Kolokoussis, Polychronis; Karathanassi, Vassilia

    2015-10-01

    This paper proposes an efficient methodology for combining multiple remotely sensed imagery, in order to increase the classification accuracy in complex forest species mapping tasks. The proposed scheme follows a decision fusion approach, whereby each image is first classified separately by means of a pixel-wise Fuzzy-Output Support Vector Machine (FO-SVM) classifier. Subsequently, the multiple results are fused according to the so-called multiple spectral- spatial classifier using the minimum spanning forest (MSSC-MSF) approach, which constitutes an effective post-regularization procedure for enhancing the result of a single pixel-based classification. For this purpose, the original MSSC-MSF has been extended in order to handle multiple classifications. In particular, the fuzzy outputs of the pixel-based classifiers are stacked and used to grow the MSF, whereas the markers are also determined considering both classifications. The proposed methodology has been tested on a challenging forest species mapping task in northern Greece, considering a multispectral (GeoEye) and a hyper-spectral (CASI) image. The pixel-wise classifications resulted in overall accuracies (OA) of 68.71% for the GeoEye and 77.95% for the CASI images, respectively. Both of them are characterized by high levels of speckle noise. Applying the proposed multi-source MSSC-MSF fusion, the OA climbs to 90.86%, which is attributed both to the ability of MSSC-MSF to tackle the salt-and-pepper effect, as well as the fact that the fusion approach exploits the relative advantages of both information sources.

  16. Characteristics of Love and Rayleigh waves in ambient noise: wavetype ratio, source location and seasonal behavior

    NASA Astrophysics Data System (ADS)

    Juretzek, C.; Perleth, M.; Hadziioannou, C.

    2015-12-01

    Ambient seismic noise has become an important source of signal for tomography and monitoring purposes. Better understanding of the noise field characteristics is crucial to further improve noise applications. Our knowledge about the common and different origins of Love and Rayleigh waves in the microseism bands is still limited. This applies in particular to constraints on source locations and source mechanisms of Love waves. Here, 3-component beamforming is used to distinguish between the differently polarized wave types present in the noise field recorded at several arrays across Europe. The focus lies on frequencies around the primary and secondary microseismic bands. We compare characteristics of Love and Rayleigh wave noise, such as source directions and frequency content. Further, Love to Rayleigh wave ratios are measured at each array, and a dependence on direction is observed. We constrain the corresponding source regions of both wave types by backprojection. By using a full year of data in 2013, we are able to track the seasonal changes in our observations of Love-to-Rayleigh ratio and source locations.

  17. Estimation of source apportionment and potential source locations of PM 2.5 at a west coastal IMPROVE site

    NASA Astrophysics Data System (ADS)

    Hwang, InJo; Hopke, Philip K.

    Particle composition data for PM 2.5 samples collected at Kalmiopsis Interagency Monitoring of Protected Visual Environments (IMPROVE) site in southwestern Oregon from March 2000 to May 2004 were analyzed to provide source identification and apportionment. A total of 493 samples were collected and 32 species were analyzed by particle induced X-ray emission, proton elastic scattering analysis, photon-induced X-ray fluorescence, ion chromatography, and thermal optical reflectance methods. Positive matrix factorization (PMF) was used to estimate the source profiles and their mass contributions. The PMF modeling identified nine sources. In the Kalmiopsis site, the average mass was apportioned to wood/field burning (38.4%), secondary sulfate (26.9%), airborne soil including Asian dust (8.6 %), secondary nitrate (7.6%), fresh sea salt (5.8%), OP-rich sulfate (4.9%), aged sea salt (4.5 %), gasoline vehicle (1.9%), and diesel emission (1.4%). The potential source contribution function (PSCF) was then used to help identify likely locations of the regional sources of pollution. The PSCF map for wood/field burning indicates there is a major potential source area in the Siskiyou County and eastern Oregon. The potential source locations for secondary sulfate are found in western Washington, northwestern Oregon, and the near shore Pacific Ocean where there are extensive shipping lanes. It was not possible to extract a profile directly attributable to ship emissions, but indications of their influence are seen in the secondary sulfate and aged sea salt compositions.

  18. Source location impact on relative tsunami strength along the U.S. West Coast

    NASA Astrophysics Data System (ADS)

    Rasmussen, L.; Bromirski, P. D.; Miller, A. J.; Arcas, D.; Flick, R. E.; Hendershott, M. C.

    2015-07-01

    Tsunami propagation simulations are used to identify which tsunami source locations would produce the highest amplitude waves on approach to key population centers along the U.S. West Coast. The reasons for preferential influence of certain remote excitation sites are explored by examining model time sequences of tsunami wave patterns emanating from the source. Distant bathymetric features in the West and Central Pacific can redirect tsunami energy into narrow paths with anomalously large wave height that have disproportionate impact on small areas of coastline. The source region generating the waves can be as little as 100 km along a subduction zone, resulting in distinct source-target pairs with sharply amplified wave energy at the target. Tsunami spectral ratios examined for transects near the source, after crossing the West Pacific, and on approach to the coast illustrate how prominent bathymetric features alter wave spectral distributions, and relate to both the timing and magnitude of waves approaching shore. To contextualize the potential impact of tsunamis from high-amplitude source-target pairs, the source characteristics of major historical earthquakes and tsunamis in 1960, 1964, and 2011 are used to generate comparable events originating at the highest-amplitude source locations for each coastal target. This creates a type of "worst-case scenario," a replicate of each region's historically largest earthquake positioned at the fault segment that would produce the most incoming tsunami energy at each target port. An amplification factor provides a measure of how the incoming wave height from the worst-case source compares to the historical event.

  19. Multiband array detection and location of seismic sources recorded by dense seismic networks

    NASA Astrophysics Data System (ADS)

    Poiata, Natalia; Satriano, Claudio; Vilotte, Jean-Pierre; Bernard, Pascal; Obara, Kazushige

    2016-06-01

    We present a new methodology for detection and space-time location of seismic sources based on multiscale, frequency-selective coherence of the wave field recorded by dense large-scale seismic networks and local antennas. The method is designed to enhance coherence of the signal statistical features across the array of sensors and consists of three steps: signal processing, space-time imaging, and detection and location. The first step provides, for each station, a simplified representation of seismic signal by extracting multiscale non-stationary statistical characteristics, through multiband higher-order statistics or envelopes. This signal processing scheme is designed to account for a priori unknown transients, potentially associated with a variety of sources (e.g. earthquakes, tremors), and to prepare data for a better performance in posterior steps. Following space-time imaging is carried through 3-D spatial mapping and summation of station-pair time-delay estimate functions. This step produces time-series of 3-D spatial images representing the likelihood that each pixel makes part of a source. Detection and location is performed in the final step by extracting the local maxima from the 3-D spatial images. We demonstrate the efficiency of the method in detecting and locating seismic sources associated with low signal-to-noise ratio on an example of the aftershock earthquake records from local stations of International Maule Aftershock Deployment in Central Chile. The performance and potential of the method to detect, locate and characterize the energy release associated with possibly mixed seismic radiation from earthquakes and low-frequency tectonic tremors is further tested on continuous data from southwestern Japan.

  20. Multi-band array detection and location of seismic sources recorded by dense seismic networks

    NASA Astrophysics Data System (ADS)

    Poiata, Natalia; Satriano, Claudio; Vilotte, Jean-Pierre; Bernard, Pascal; Obara, Kazushige

    2016-02-01

    We present a new methodology for detection and space-time location of seismic sources based on multi-scale, frequency-selective coherence of the wave field recorded by dense large-scale seismic networks and local antennas. The method is designed to enhance coherence of the signal statistical features across the array of sensors and consists of three steps: signal processing, space-time imaging, and detection and location. The first step provides, for each station, a simplified representation of seismic signal by extracting multi-scale non-stationary statistical characteristics, through multi-band higher-order statistics or envelopes. This signal processing scheme is designed to account for a priori unknown transients, potentially associated with a variety of sources (e.g., earthquakes, tremors), and to prepare data for a better performance in posterior steps. Following space-time imaging is carried through 3D spatial mapping and summation of station-pair time-delay estimate functions. This step produces time series of 3D spatial images representing the likelihood that each pixel makes part of a source. Detection and location is performed in the final step by extracting the local maxima from the 3D spatial images. We demonstrate the efficiency of the method in detecting and locating seismic sources associated with low signal-to-noise ratio on an example of the aftershock earthquake records from local stations of International Maule Aftershock Deployment in Central Chile. The performance and potential of the method to detect, locate and characterize the energy release associated with possibly mixed seismic radiation from earthquakes and low-frequency tectonic tremors is further tested on continuous data from southwestern Japan.

  1. Localizer: fast, accurate, open-source, and modular software package for superresolution microscopy.

    PubMed

    Dedecker, Peter; Duwé, Sam; Neely, Robert K; Zhang, Jin

    2012-12-01

    We present Localizer, a freely available and open source software package that implements the computational data processing inherent to several types of superresolution fluorescence imaging, such as localization (PALM/STORM/GSDIM) and fluctuation imaging (SOFI/pcSOFI). Localizer delivers high accuracy and performance and comes with a fully featured and easy-to-use graphical user interface but is also designed to be integrated in higher-level analysis environments. Due to its modular design, Localizer can be readily extended with new algorithms as they become available, while maintaining the same interface and performance. We provide front-ends for running Localizer from Igor Pro, Matlab, or as a stand-alone program. We show that Localizer performs favorably when compared with two existing superresolution packages, and to our knowledge is the only freely available implementation of SOFI/pcSOFI microscopy. By dramatically improving the analysis performance and ensuring the easy addition of current and future enhancements, Localizer strongly improves the usability of superresolution imaging in a variety of biomedical studies. PMID:23208219

  2. Acoustic emission source location on large plate-like structures using a local triangular sensor array

    NASA Astrophysics Data System (ADS)

    Aljets, Dirk; Chong, Alex; Wilcox, Steve; Holford, Karen

    2012-07-01

    A new acoustic emission (AE) source location method was developed for large plate-like structures, which evaluates the location of the source using a combined time of flight and modal source location algorithm. Three sensors are installed in a triangular array with a sensor to sensor distance of just a few centimeters. The direction from the sensor array to the AE source can be established by analysing the arrival times of the A0 component of the signal to the three sensors whilst the distance can be evaluated using the separation of S0 and A0 mode at each sensor respectively. The close positioning of the sensors allows the array to be installed in a single housing. This simplifies mounting, wiring and calibration procedures for non-destructive testing (NDT) and structural health monitoring (SHM) applications. Furthermore, this array could reduce the number of sensors needed to monitor large structures compared to other methods. An automatic wave mode identification method is also presented.

  3. Quantifying uncertainties in location and source mechanism for Long-Period events at Mt Etna, Italy.

    NASA Astrophysics Data System (ADS)

    Cauchie, Léna; Saccorotti, Gilberto; Bean, Christopher

    2014-05-01

    The manifestation of Long-Period events is documented at many volcanoes worldwide. However the mechanism at their origin is still object of discussion. Models proposed so far involve (i) the resonance of fluid-filled cracks or conduits that are triggered by fluid instabilities or the brittle failure of high viscous magmas and (ii) the slow-rupture earthquakes in the shallow portion of volcanic edifices. Since LP activity usually precedes and accompanies volcanic eruption, the understanding of these sources is important in terms of hazard assessment and eruption early warning. The work is thus primarily aimed at the assessment of the uncertainties in the determination of LP source properties as a consequence of poor knowledge of the velocity structure and location errors. We used data from temporary networks deployed on Mt Etna in 2005. During August, 2005, about 13000 LP events were detected through a STA/LTA approach, and were classified into two families on the basis of waveform similarity. For each family of events, we located the source using three different approaches: (1) a single-station-location method based on the back-propagation of the polarization vector estimated from covariance analysis of three-component signals; (2) multi-channel analysis of data recorded by two seismic arrays; (3) relative locations based on inversion of differential times obtained through cross-correlation of similar waveforms. For all these three different methods, the solutions are very sensitive to the chosen velocity model. We thus iterated the location procedure for different medium properties; the preferred velocity is that for which the results obtained with the three different methods are consistent each other. For each family, we then defined a volume of possible source location and performed a full-waveform, moment tensor (MT) inversion for the entire catalog of events. In this manner, we obtained a MT solution for each grid node of the investigated volume. The MT

  4. Gravitational wave hotspots: Ranking potential locations of single-source gravitational wave emission

    SciTech Connect

    Simon, Joseph; Polin, Abigail; Lommen, Andrea; Christy, B; Stappers, Ben; Finn, Lee Samuel; Jenet, F. A.

    2014-03-20

    The steadily improving sensitivity of pulsar timing arrays (PTAs) suggests that gravitational waves (GWs) from supermassive black hole binary (SMBHB) systems in the nearby universe will be detectable sometime during the next decade. Currently, PTAs assume an equal probability of detection from every sky position, but as evidence grows for a non-isotropic distribution of sources, is there a most likely sky position for a detectable single source of GWs? In this paper, a collection of Galactic catalogs is used to calculate various metrics related to the detectability of a single GW source resolvable above a GW background, assuming that every galaxy has the same probability of containing an SMBHB. Our analyses of these data reveal small probabilities that one of these sources is currently in the PTA band, but as sensitivity is improved regions of consistent probability density are found in predictable locations, specifically around local galaxy clusters.

  5. Acoustic emission non-destructive testing of structures using source location techniques.

    SciTech Connect

    Beattie, Alan G.

    2013-09-01

    The technology of acoustic emission (AE) testing has been advanced and used at Sandia for the past 40 years. AE has been used on structures including pressure vessels, fire bottles, wind turbines, gas wells, nuclear weapons, and solar collectors. This monograph begins with background topics in acoustics and instrumentation and then focuses on current acoustic emission technology. It covers the overall design and system setups for a test, with a wind turbine blade as the object. Test analysis is discussed with an emphasis on source location. Three test examples are presented, two on experimental wind turbine blades and one on aircraft fire extinguisher bottles. Finally, the code for a FORTRAN source location program is given as an example of a working analysis program. Throughout the document, the stress is on actual testing of real structures, not on laboratory experiments.

  6. An evaluation of effective radiuses of bulk-wave ultrasonic transducers as circular piston sources for accurate velocity measurements.

    PubMed

    Arakawa, Mototaka; Kushibiki, Jun-ichi; Aoki, Naoya

    2004-05-01

    The effective radius of a bulk-wave ultrasonic transducer as a circular piston source, fabricated on one end of a synthetic silica (SiO2) glass buffer rod, was evaluated for accurate velocity measurements of dispersive specimens over a wide frequency range. The effective radius was determined by comparing measured and calculated phase variations due to diffraction in an ultrasonic transmission line of the SiO2 buffer rod/water-couplant/SiO2 standard specimen, using radio-frequency (RF) tone burst ultrasonic waves. Fourteen devices with different device parameters were evaluated. The velocities of the nondispersive standard specimen (C-7940) were found to be 5934.10 +/- 0.35 m/s at 70 to 290 MHz, after diffraction correction using the nominal radius (0.75 mm) for an ultrasonic device with an operating center frequency of about 400 MHz. Corrected velocities were more accurately found to be 5934.15 +/- 0.03 m/s by using the effective radius (0.780 mm) for the diffraction correction. Bulk-wave ultrasonic devices calibrated by this experimental procedure enable conducting extremely accurate velocity dispersion measurements. PMID:15217227

  7. a Study of Microphone Arrays for the Location of Vibrational Sound Sources

    NASA Astrophysics Data System (ADS)

    Matzumoto, Andres Esteban Perez

    Available from UMI in association with The British Library. The original objective of the work was to develop an acoustic imaging technique, Nearfield Acoustic Holography (NAH), into a reasonably affordable practical system for in-situ applications in an industrial environment. In order to place NAH in the general context of source identification techniques, the thesis summarizes theoretical considerations about sound sources and sound fields, and the principles of different sound source location techniques used in practical situations. The development of NAH theory for planar arrays is the central point of this summary, and the different systems that apply this theory are discussed. Theoretical research and computer simulations show that, at the present state of the art, sound source reconstructions using NAH can only work in certain cases which have to be analyzed individually. The limitations of the theory are better understood when the source reconstruction is studied using the proper methodology for the inherent ill-posed inverse problem. Such as study allowed us to improve the theoretical framework, and to obtain stable source reconstructions. A reliable system for field measurements of different types of sources was not found to be feasible at present. However, it is shown that the inverse problem theory allows us to overcome some of the limitations of the current theory for field measurements. The difficulties encountered with NAH, and the study of the inverse problem, led us to attempt to develop an alternative, simpler, system which could minimize the inverse problem of source reconstruction. The system considered was a hemispherical array with analogue signal processing. Applying this principle transforms the source reconstruction problem into a re-modelling problem, reducing the inverse problem to the solution of a stable direct problem. Although the antenna could not be tested to its full potential, the initial results were not applicable for source

  8. Sharks need the lateral line to locate odor sources: rheotaxis and eddy chemotaxis.

    PubMed

    Gardiner, Jayne M; Atema, Jelle

    2007-06-01

    Odor plumes are complex, dynamic, three-dimensional structures used by many animals to locate food, mates, home sites, etc. Yet odor itself has no directional properties. Animals use a variety of different senses to obtain directional information. Since most odor plumes are composed of dispersing odor patches and dissipating vorticity eddies, aquatic animals may localize odor sources by simultaneous analysis of chemical and hydrodynamic dispersal fields, a process referred to as eddy chemotaxis. This study examines the contributions of olfaction, mechanoreception and vision to odor source localization in a shark, the smooth dogfish Mustelus canis. Two parallel, turbulent plumes were created in an 8 m flume: squid rinse odor and seawater control. Minimally turbulent ;oozing' sources of odor and seawater control were physically separated from sources of major turbulence by placing a brick downstream from each oozing source, creating two turbulent wakes, one or the other flavored with food odor. This created four separate targets for the sharks to locate. Animals were tested under two light conditions (fluorescent and infrared) and in two sensory conditions (lateral line intact and lateral line lesioned by streptomycin). Intact animals demonstrated a preference for the odor plume over the seawater plume and for the source of odor/turbulence (the brick on the odor side) over the source of the odor alone (the odor-oozing nozzle). Plume and target preference and search time were not significantly affected by light condition. In the light, lesioning the lateral line increased search time but did not affect success rate or plume preference. However, lesioned animals no longer discriminated between sources of turbulent and oozing odor. In the dark, search time of lesioned animals further increased, and the few animals that located any of the targets did not discriminate between odor and seawater plumes, let alone targets. These results demonstrate for the first time that

  9. Reconstruction of the activity of point sources for the accurate characterization of nuclear waste drums by segmented gamma scanning.

    PubMed

    Krings, Thomas; Mauerhofer, Eric

    2011-06-01

    This work improves the reliability and accuracy in the reconstruction of the total isotope activity content in heterogeneous nuclear waste drums containing point sources. The method is based on χ(2)-fits of the angular dependent count rate distribution measured during a drum rotation in segmented gamma scanning. A new description of the analytical calculation of the angular count rate distribution is introduced based on a more precise model of the collimated detector. The new description is validated and compared to the old description using MCNP5 simulations of angular dependent count rate distributions of Co-60 and Cs-137 point sources. It is shown that the new model describes the angular dependent count rate distribution significantly more accurate compared to the old model. Hence, the reconstruction of the activity is more accurate and the errors are considerably reduced that lead to more reliable results. Furthermore, the results are compared to the conventional reconstruction method assuming a homogeneous matrix and activity distribution. PMID:21353575

  10. BlueDetect: An iBeacon-Enabled Scheme for Accurate and Energy-Efficient Indoor-Outdoor Detection and Seamless Location-Based Service

    PubMed Central

    Zou, Han; Jiang, Hao; Luo, Yiwen; Zhu, Jianjie; Lu, Xiaoxuan; Xie, Lihua

    2016-01-01

    The location and contextual status (indoor or outdoor) is fundamental and critical information for upper-layer applications, such as activity recognition and location-based services (LBS) for individuals. In addition, optimizations of building management systems (BMS), such as the pre-cooling or heating process of the air-conditioning system according to the human traffic entering or exiting a building, can utilize the information, as well. The emerging mobile devices, which are equipped with various sensors, become a feasible and flexible platform to perform indoor-outdoor (IO) detection. However, power-hungry sensors, such as GPS and WiFi, should be used with caution due to the constrained battery storage on mobile device. We propose BlueDetect: an accurate, fast response and energy-efficient scheme for IO detection and seamless LBS running on the mobile device based on the emerging low-power iBeacon technology. By leveraging the on-broad Bluetooth module and our proposed algorithms, BlueDetect provides a precise IO detection service that can turn on/off on-board power-hungry sensors smartly and automatically, optimize their performances and reduce the power consumption of mobile devices simultaneously. Moreover, seamless positioning and navigation services can be realized by it, especially in a semi-outdoor environment, which cannot be achieved by GPS or an indoor positioning system (IPS) easily. We prototype BlueDetect on Android mobile devices and evaluate its performance comprehensively. The experimental results have validated the superiority of BlueDetect in terms of IO detection accuracy, localization accuracy and energy consumption. PMID:26907295

  11. BlueDetect: An iBeacon-Enabled Scheme for Accurate and Energy-Efficient Indoor-Outdoor Detection and Seamless Location-Based Service.

    PubMed

    Zou, Han; Jiang, Hao; Luo, Yiwen; Zhu, Jianjie; Lu, Xiaoxuan; Xie, Lihua

    2016-01-01

    The location and contextual status (indoor or outdoor) is fundamental and critical information for upper-layer applications, such as activity recognition and location-based services (LBS) for individuals. In addition, optimizations of building management systems (BMS), such as the pre-cooling or heating process of the air-conditioning system according to the human traffic entering or exiting a building, can utilize the information, as well. The emerging mobile devices, which are equipped with various sensors, become a feasible and flexible platform to perform indoor-outdoor (IO) detection. However, power-hungry sensors, such as GPS and WiFi, should be used with caution due to the constrained battery storage on mobile device. We propose BlueDetect: an accurate, fast response and energy-efficient scheme for IO detection and seamless LBS running on the mobile device based on the emerging low-power iBeacon technology. By leveraging the on-broad Bluetooth module and our proposed algorithms, BlueDetect provides a precise IO detection service that can turn on/off on-board power-hungry sensors smartly and automatically, optimize their performances and reduce the power consumption of mobile devices simultaneously. Moreover, seamless positioning and navigation services can be realized by it, especially in a semi-outdoor environment, which cannot be achieved by GPS or an indoor positioning system (IPS) easily. We prototype BlueDetect on Android mobile devices and evaluate its performance comprehensively. The experimental results have validated the superiority of BlueDetect in terms of IO detection accuracy, localization accuracy and energy consumption. PMID:26907295

  12. The location of the source of high-frequency solar acoustic oscillations

    SciTech Connect

    Kumar, Pawan; Lu, Edward )

    1991-07-01

    Recently Libbrecht and Jefferies et al. have reported regular peaks in the solar oscillation power spectrum extending well above 5.3 mHz, the maximum frequency of trapped acoustic modes. Kumar et al. argued that these peaks are primarily due to the interference of traveling waves which are excited due to acoustic emission from turbulent convection. In contrast with the standing wave P-mode frequencies below 5.3 mHz, the positions of the high-frequency interference peaks (HIPs) are dependent on the location of the source of the acoustic oscillations. In the present work, Kumar et al.'s argument is strengthened, and more importantly, use is made of the above dependence to determine the acoustic source strength as a function of depth. It is found that the acoustic source profile, and thus the convective velocity, is peaked about 200 km deeper than what is expected from standard mixing length theory. 13 refs.

  13. Statistical study of coronal mass ejection source locations: Understanding CMEs viewed in coronagraphs

    NASA Astrophysics Data System (ADS)

    Wang, Yuming; Chen, Caixia; Gui, Bin; Shen, Chenglong; Ye, Pinzhong; Wang, S.

    2011-04-01

    How to properly understand coronal mass ejections (CMEs) viewed in white light coronagraphs is crucial to many relative researches in solar and space physics. The issue is now particularly addressed in this paper through studying the source locations of all the 1078 Large Angle and Spectrometric Coronagraph (LASCO) CMEs listed in Coordinated Data Analysis Workshop (CDAW) CME catalog during 1997-1998 and their correlation with CMEs' apparent parameters. By manually checking LASCO and Extreme Ultraviolet Imaging Telescope (EIT) movies of these CMEs, we find that, except 231 CMEs whose source locations cannot be identified due to poor data, there are 288 CMEs with location identified on the frontside solar disk, 234 CMEs appearing above solar limb, and 325 CMEs without evident eruptive signatures in the field of view of EIT. On the basis of the statistical results of CMEs' source locations, there are four physical issues: (1) the missing rate of CMEs by SOHO LASCO and EIT, (2) the mass of CMEs, (3) the causes of halo CMEs, and (4) the deflections of CMEs in the corona, are exhaustively analyzed. It is found that (1) about 32% frontside CMEs cannot be recognized by SOHO, (2) the brightness of a CME at any heliocentric distance is roughly positively correlated with its speed, and the CME mass derived from the brightness is probably overestimated, (3) both projection effect and violent eruption are the major causes of halo CMEs, and especially for limb halo CMEs the latter is the primary one, and (4) most CMEs deflected toward equator near the solar minimum; these deflections can be classified into three types: the asymmetrical expansion, the nonradial ejection, and the deflected propagation.

  14. An Improved Source-Scanning Algorithm for Locating Earthquake Clusters or Aftershock Sequences

    NASA Astrophysics Data System (ADS)

    Liao, Y.; Kao, H.; Hsu, S.

    2010-12-01

    The Source-scanning Algorithm (SSA) was originally introduced in 2004 to locate non-volcanic tremors. Its application was later expanded to the identification of earthquake rupture planes and the near-real-time detection and monitoring of landslides and mud/debris flows. In this study, we further improve SSA for the purpose of locating earthquake clusters or aftershock sequences when only a limited number of waveform observations are available. The main improvements include the application of a ground motion analyzer to separate P and S waves, the automatic determination of resolution based on the grid size and time step of the scanning process, and a modified brightness function to utilize constraints from multiple phases. Specifically, the improved SSA (named as ISSA) addresses two major issues related to locating earthquake clusters/aftershocks. The first one is the massive amount of both time and labour to locate a large number of seismic events manually. And the second one is to efficiently and correctly identify the same phase across the entire recording array when multiple events occur closely in time and space. To test the robustness of ISSA, we generate synthetic waveforms consisting of 3 separated events such that individual P and S phases arrive at different stations in different order, thus making correct phase picking nearly impossible. Using these very complicated waveforms as the input, the ISSA scans all model space for possible combination of time and location for the existence of seismic sources. The scanning results successfully associate various phases from each event at all stations, and correctly recover the input. To further demonstrate the advantage of ISSA, we apply it to the waveform data collected by a temporary OBS array for the aftershock sequence of an offshore earthquake southwest of Taiwan. The overall signal-to-noise ratio is inadequate for locating small events; and the precise arrival times of P and S phases are difficult to

  15. Transport of perfluoroalkyl substances (PFAS) from an arctic glacier to downstream locations: implications for sources.

    PubMed

    Kwok, Karen Y; Yamazaki, Eriko; Yamashita, Nobuyoshi; Taniyasu, Sachi; Murphy, Margaret B; Horii, Yuichi; Petrick, Gert; Kallerborn, Roland; Kannan, Kurunthachalam; Murano, Kentaro; Lam, Paul K S

    2013-03-01

    Perfluoroalkyl substances (PFAS) have been globally detected in various environmental matrices, yet their fate and transport to the Arctic is still unclear, especially for the European Arctic. In this study, concentrations of 17 PFAS were quantified in two ice cores (n=26), surface snow (n=9) and surface water samples (n=14) collected along a spatial gradient in Svalbard, Norway. Concentrations of selected ions (Na(+), SO4(2-), etc.) were also determined for tracing the origins and sources of PFAS. Perfluorobutanoate (PFBA), perfluorooctanoate (PFOA) and perfluorononanoate (PFNA) were the dominant compounds found in ice core samples. Taking PFOA, PFNA and perfluorooctane-sulfonate (PFOS) as examples, higher concentrations were detected in the middle layers of the ice cores representing the period of 1997-2000. Lower concentrations of C8-C12 perfluorocarboxylates (PFCAs) were detected in comparison with concentrations measured previously in an ice core from the Canadian Arctic, indicating that contamination levels in the European Arctic are lower. Average PFAS concentrations were found to be lower in surface snow and melted glacier water samples, while increased concentrations were observed in river water downstream near the coastal area. Perfluorohexanesulfonate (PFHxS) was detected in the downstream locations, but not in the glacier, suggesting existence of local sources of this compound. Long-range atmospheric transport of PFAS was the major deposition pathway for the glaciers, while local sources (e.g., skiing activities) were identified in the downstream locations. PMID:23376515

  16. A Method for Monitoring the Underground Mining Position Based on the Blasting Source Location

    NASA Astrophysics Data System (ADS)

    Meng, Xiu-zhi; Wang, Zong-sheng; Zhang, Zeng-zhi; Wang, Feng-qian

    2013-01-01

    Some small and medium-sized coal mines are mining beyond their mining boundary driven by profit. The illegal activities cause many mine disasters but effective supervision is very hard to achieve, especially for underground coal mining. Nowadays, artificial blasting operation is widely used in tunneling or mining in small and medium-sized coal mines. A method for monitoring the underground mining position by monitoring the blasting source position is firstly introduced in this paper. The blasting vibration waves are picked up by the detectors and dealt by the signal acquisition sub-station, and then sent to the principal computer. The blasting source is located by the principal computer and displayed in the mine’s electronic map. The blasting source position is located in 10 seconds after the first P wave reaching the detector, whose error is registered within 20 meters by field-proven method. Auto-monitoring of the underground mining position in real-time is solved better and management level is improved using this method.

  17. Identification of efficient observers for locating spreading source in complex networks

    NASA Astrophysics Data System (ADS)

    Zhang, Xizhe; Zhang, Yubo; Lv, Tianyang; Yin, Ying

    2016-01-01

    Estimating the location of the spreading source of complex networks is a challenging task and plays an important role in many real problems. The hidden source can be localized based on the information gathered by a few nodes, which are called the observers. Identification of the efficient observers is critical to locate the source with high accuracy. Here we analyze several placement strategies of the observers based on centralities of nodes, including the high-degree, high-betweenness, high-clustering coefficient, high-eigenvector and high-closeness. Based on the random spreading experiments on both model and real networks, we find that the localization accuracy of these strategies is decreased with the increase of the connectivity of network, and there is no significant difference between them. Further experiments show that the coverage range of the observers may be the key factor that affects the localization accuracy. Our results can provide a route for the optimal design of placement strategies of the observer nodes.

  18. Source location and characterization of volatile organic compound emissions at a petrochemical plant in Kaohsiung, Taiwan.

    PubMed

    Chen, Chin-Liang; Fang, Hung Yuan; Shu, Chi-Min

    2005-10-01

    This paper elucidated a novel approach to locating volatile organic compound (VOC) emission sources and characterizing their VOCs by database and contour plotting. The target of this survey was a petrochemical plant in Linyan, Kaohsiung County, Taiwan. Samples were taken with canisters from 25 sites inside this plant, twice per season, and analyzed by gas chromatography-mass spectrometry. The survey covered 1 whole year. By consolidated into a database, the data could be readily retrieved, statistically analyzed, and clearly presented in both table and graph forms. It followed from the cross-analysis of the database that the abundant types of VOCs were alkanes, alkenes/dienes, and aromatics, all of which accounted for 99% of total VOCs. By contour plotting, the emission sources for alkanes, aromatics, and alkenes/ dienes were successfully located. Through statistical analysis, the database could provide the range and 90% confidence interval of each species from each emission source. Both alkanes and alkene/dienes came from tank farm and naphtha cracking units and were mainly composed of C3-C5 members. Regarding aromatics, benzene, toluene, and xylenes were the primary species; they were emitted from tank farm, aromatic units, and xylene units. PMID:16295274

  19. A subsurface structure change associated with the eruptive activity at Sakurajima Volcano, Japan, inferred from an accurately controlled source

    NASA Astrophysics Data System (ADS)

    Maeda, Yuta; Yamaoka, Koshun; Miyamachi, Hiroki; Watanabe, Toshiki; Kunitomo, Takahiro; Ikuta, Ryoya; Yakiwara, Hiroshi; Iguchi, Masato

    2015-07-01

    Temporal variations of Green functions associated with the eruptive activity at Sakurajima Volcano, Japan, were estimated using an accurately controlled routinely operated signal system (ACROSS). We deconvolved 400 s waveforms of the ACROSS signal at nearby stations by a known source time function and stacked the results based on the time relative to individual eruptions and the eruption intervals; the quantities obtained by this procedure are Green functions corresponding to various stages of the eruptive activity. We found an energy decrease in the later phase of the Green functions in active eruptive periods. This energy decrease, localized in the 2-6 s window of the Green functions, is difficult to explain by contamination from volcanic earthquakes and tremors. The decrease could be more reasonably attributed to a subsurface structure change caused by the volcanic activity.

  20. Rapid Bayesian point source inversion using pattern recognition --- bridging the gap between regional scaling relations and accurate physical modelling

    NASA Astrophysics Data System (ADS)

    Valentine, A. P.; Kaeufl, P.; De Wit, R. W. L.; Trampert, J.

    2014-12-01

    Obtaining knowledge about source parameters in (near) real-time during or shortly after an earthquake is essential for mitigating damage and directing resources in the aftermath of the event. Therefore, a variety of real-time source-inversion algorithms have been developed over recent decades. This has been driven by the ever-growing availability of dense seismograph networks in many seismogenic areas of the world and the significant advances in real-time telemetry. By definition, these algorithms rely on short time-windows of sparse, local and regional observations, resulting in source estimates that are highly sensitive to observational errors, noise and missing data. In order to obtain estimates more rapidly, many algorithms are either entirely based on empirical scaling relations or make simplifying assumptions about the Earth's structure, which can in turn lead to biased results. It is therefore essential that realistic uncertainty bounds are estimated along with the parameters. A natural means of propagating probabilistic information on source parameters through the entire processing chain from first observations to potential end users and decision makers is provided by the Bayesian formalism.We present a novel method based on pattern recognition allowing us to incorporate highly accurate physical modelling into an uncertainty-aware real-time inversion algorithm. The algorithm is based on a pre-computed Green's functions database, containing a large set of source-receiver paths in a highly heterogeneous crustal model. Unlike similar methods, which often employ a grid search, we use a supervised learning algorithm to relate synthetic waveforms to point source parameters. This training procedure has to be performed only once and leads to a representation of the posterior probability density function p(m|d) --- the distribution of source parameters m given observations d --- which can be evaluated quickly for new data.Owing to the flexibility of the pattern

  1. Do locations of CME source regions relative to the HSB determine the appearance of the CME?

    NASA Astrophysics Data System (ADS)

    Li, Y.; Luhmann, J. G.; Zhao, X. P.

    2002-05-01

    The relationship between CMEs and the coronal helmet streamer belt has been the subject of several studies. Recent studies using SOHO/LASCO observation presented a rather complicated picture of this relationship (Subramanian et al., 1999). It has been suggested that a CME may blowout, create, disturb, have no effect on or be clearly displaced from a streamer. We investigate the possibility that these different interactions may be due to the locations of the CME source regions relative to the helmet streamer belt. Estimated Helmet streamer belt configurations obtained using Potential Field Source Surface Models based on SOHO/MDI synoptic maps are compared with combined LASCO-EIT movies on the LASCO website for this study.

  2. Locating and Quantifying Broadband Fan Sources Using In-Duct Microphones

    NASA Technical Reports Server (NTRS)

    Dougherty, Robert P.; Walker, Bruce E.; Sutliff, Daniel L.

    2010-01-01

    In-duct beamforming techniques have been developed for locating broadband noise sources on a low-speed fan and quantifying the acoustic power in the inlet and aft fan ducts. The NASA Glenn Research Center's Advanced Noise Control Fan was used as a test bed. Several of the blades were modified to provide a broadband source to evaluate the efficacy of the in-duct beamforming technique. Phased arrays consisting of rings and line arrays of microphones were employed. For the imaging, the data were mathematically resampled in the frame of reference of the rotating fan. For both the imaging and power measurement steps, array steering vectors were computed using annular duct modal expansions, selected subsets of the cross spectral matrix elements were used, and the DAMAS and CLEAN-SC deconvolution algorithms were applied.

  3. UTILIZING RESULTS FROM INSAR TO DEVELOP SEISMIC LOCATION BENCHMARKS AND IMPLICATIONS FOR SEISMIC SOURCE STUDIES

    SciTech Connect

    M. BEGNAUD; ET AL

    2000-09-01

    Obtaining accurate seismic event locations is one of the most important goals for monitoring detonations of underground nuclear teats. This is a particular challenge at small magnitudes where the number of recording stations may be less than 20. Although many different procedures are being developed to improve seismic location, most procedures suffer from inadequate testing against accurate information about a seismic event. Events with well-defined attributes, such as latitude, longitude, depth and origin time, are commonly referred to as ground truth (GT). Ground truth comes in many forms and with many different levels of accuracy. Interferometric Synthetic Aperture Radar (InSAR) can provide independent and accurate information (ground truth) regarding ground surface deformation and/or rupture. Relating surface deformation to seismic events is trivial when events are large and create a significant surface rupture, such as for the M{sub w} = 7.5 event that occurred in the remote northern region of the Tibetan plateau in 1997. The event, which was a vertical strike slip even appeared anomalous in nature due to the lack of large aftershocks and had an associated surface rupture of over 180 km that was identified and modeled using InSAR. The east-west orientation of the fault rupture provides excellent ground truth for latitude, but is of limited use for longitude. However, a secondary rupture occurred 50 km south of the main shock rupture trace that can provide ground truth with accuracy within 5 km. The smaller, 5-km-long secondary rupture presents a challenge for relating the deformation to a seismic event. The rupture is believed to have a thrust mechanism; the dip of the fimdt allows for some separation between the secondary rupture trace and its associated event epicenter, although not as much as is currently observed from catalog locations. Few events within the time period of the InSAR analysis are candidates for the secondary rupture. Of these, we have

  4. Reconstruction of source location in a network of gravitational wave interferometric detectors

    SciTech Connect

    Cavalier, Fabien; Barsuglia, Matteo; Bizouard, Marie-Anne; Brisson, Violette; Clapson, Andre-Claude; Davier, Michel; Hello, Patrice; Kreckelbergh, Stephane; Leroy, Nicolas; Varvella, Monica

    2006-10-15

    This paper deals with the reconstruction of the direction of a gravitational wave source using the detection made by a network of interferometric detectors, mainly the LIGO and Virgo detectors. We suppose that an event has been seen in coincidence using a filter applied on the three detector data streams. Using the arrival time (and its associated error) of the gravitational signal in each detector, the direction of the source in the sky is computed using a {chi}{sup 2} minimization technique. For reasonably large signals (SNR>4.5 in all detectors), the mean angular error between the real location and the reconstructed one is about 1 deg. . We also investigate the effect of the network geometry assuming the same angular response for all interferometric detectors. It appears that the reconstruction quality is not uniform over the sky and is degraded when the source approaches the plane defined by the three detectors. Adding at least one other detector to the LIGO-Virgo network reduces the blind regions and in the case of 6 detectors, a precision less than 1 deg. on the source direction can be reached for 99% of the sky.

  5. Investigation of source location determination from Magsat magnetic anomalies: The Euler method approach

    NASA Technical Reports Server (NTRS)

    Ravat, Dhananjay

    1996-01-01

    The applicability of the Euler method of source location determination was investigated on several model situations pertinent to satellite-data scale situations as well as Magsat data of Europe. Our investigations enabled us to understand the end-member cases for which the Euler method will work with the present satellite magnetic data and also the cases for which the assumptions implicit in the Euler method will not be met by the present satellite magnetic data. These results have been presented in one invited lecture at the Indo-US workshop on Geomagnetism in Studies of the Earth's Interior in August 1994 in Pune, India, and at one presentation at the 21st General Assembly of the IUGG in July 1995 in Boulder, CO. A new method, called Anomaly Attenuation Rate (AAR) Method (based on the Euler method), was developed during this study. This method is scale-independent and is appropriate to locate centroids of semi-compact three dimensional sources of gravity and magnetic anomalies. The method was presented during 1996 Spring AGU meeting and a manuscript describing this method is being prepared for its submission to a high-ranking journal. The grant has resulted in 3 papers and presentations at national and international meetings and one manuscript of a paper (to be submitted shortly to a reputable journal).

  6. The source location of Jovian millisecond radio bursts with respect to Jupiter's magnetic field

    NASA Technical Reports Server (NTRS)

    Genova, Francoise; Calvert, Wynne

    1988-01-01

    The location of the source of the Jovian S bursts was studied by comparing the high-frequency limit of these emissions, recorded in Nancay, to the surface gyrofrequency at the foot of the magnetic field lines which intersect Io's orbit, according to the O4 magnetic field model. For this purpose, the statistical occurrence of the S bursts was examined, both in central meridian longitude versus Io phase and as a function of the relative phase of Io with respect to Jupiter. The S bursts and the Io-dependent L emissions were found to originate from approximately the same locations at Jupiter, and probably under similar conditions of excitation by Io, although the beaming of these S emissions, which is indicated by the compactness of the occurrence patterns, was somewhat narrower than for the corresponding L emissions. Also, like the L emissions, an apparent delay of up to 70 deg was found to occur between the predicted instanteneous Io flux tube and the apparent source field line. The possible origin of this 70 deg delay is discussed.

  7. Solving seismological problems using SGRAPH program: I-source parameters and hypocentral location

    SciTech Connect

    Abdelwahed, Mohamed F.

    2012-09-26

    SGRAPH program is considered one of the seismological programs that maintain seismic data. SGRAPH is considered unique for being able to read a wide range of data formats and manipulate complementary tools in different seismological subjects in a stand-alone Windows-based application. SGRAPH efficiently performs the basic waveform analysis and solves advanced seismological problems. The graphical user interface (GUI) utilities and the Windows facilities such as, dialog boxes, menus, and toolbars simplified the user interaction with data. SGRAPH supported the common data formats like, SAC, SEED, GSE, ASCII, and Nanometrics Y-format, and others. It provides the facilities to solve many seismological problems with the built-in inversion and modeling tools. In this paper, I discuss some of the inversion tools built-in SGRAPH related to source parameters and hypocentral location estimation. Firstly, a description of the SGRAPH program is given discussing some of its features. Secondly, the inversion tools are applied to some selected events of the Dahshour earthquakes as an example of estimating the spectral and source parameters of local earthquakes. In addition, the hypocentral location of these events are estimated using the Hypoinverse 2000 program operated by SGRAPH.

  8. Relation Between Sprite Distribution and Source Locations of VHF Pulses Derived From JEM- GLIMS Measurements

    NASA Astrophysics Data System (ADS)

    Sato, Mitsuteru; Mihara, Masahiro; Ushio, Tomoo; Morimoto, Takeshi; Kikuchi, Hiroshi; Adachi, Toru; Suzuki, Makoto; Yamazaki, Atsushi; Takahashi, Yukihiro

    2015-04-01

    JEM-GLIMS is continuing the comprehensive nadir observations of lightning and TLEs using optical instruments and electromagnetic wave receivers since November 2012. For the period between November 20, 2012 and November 30, 2014, JEM-GLIMS succeeded in detecting 5,048 lightning events. A total of 567 events in 5,048 lightning events were TLEs, which were mostly elves events. To identify the sprite occurrences from the transient optical flash data, it is necessary to perform the following data analysis: (1) a subtraction of the appropriately scaled wideband camera data from the narrowband camera data; (2) a calculation of intensity ratio between different spectrophotometer channels; and (3) an estimation of the polarization and CMC for the parent CG discharges using ground-based ELF measurement data. From a synthetic comparison of these results, it is confirmed that JEM-GLISM succeeded in detecting sprite events. The VHF receiver (VITF) onboard JEM-GLIMS uses two patch-type antennas separated by a 1.6-m interval and can detect VHF pulses emitted by lightning discharges in the 70-100 MHz frequency range. Using both an interferometric technique and a group delay technique, we can estimate the source locations of VHF pulses excited by lightning discharges. In the event detected at 06:41:15.68565 UT on June 12, 2014 over central North America, sprite was distributed with a horizontal displacement of 20 km from the peak location of the parent lightning emission. In this event, a total of 180 VHF pulses were simultaneously detected by VITF. From the detailed data analysis of these VHF pulse data, it is found that the majority of the source locations were placed near the area of the dim lightning emission, which may imply that the VHF pulses were associated with the in-cloud lightning current. At the presentation, we will show detailed comparison between the spatiotemporal characteristics of sprite emission and source locations of VHF pulses excited by the parent lightning

  9. Long Period (LP) volcanic earthquake source location at Merapi volcano by using dense array technics

    NASA Astrophysics Data System (ADS)

    Metaxian, Jean Philippe; Budi Santoso, Agus; Laurin, Antoine; Subandriyo, Subandriyo; Widyoyudo, Wiku; Arshab, Ghofar

    2015-04-01

    Since 2010, Merapi shows unusual activity compared to last decades. Powerful phreatic explosions are observed; some of them are preceded by LP signals. In the literature, LP seismicity is thought to be originated within the fluid, and therefore to be representative of the pressurization state of the volcano plumbing system. Another model suggests that LP events are caused by slow, quasi-brittle, low stress-drop failure driven by transient upper-edifice deformations. Knowledge of the spatial distribution of LP events is fundamental for better understanding the physical processes occurring in the conduit, as well as for the monitoring and the improvement of eruption forecasting. LP events recorded at Merapi have a spectral content dominated by frequencies between 0.8 and 3 Hz. To locate the source of these events, we installed a seismic antenna composed of 4 broadband CMG-6TD Güralp stations. This network has an aperture of 300 m. It is located on the site of Pasarbubar, between 500 and 800 m from the crater rim. Two multi-parameter stations (seismic, tiltmeter, S-P) located in the same area, equipped with broadband CMG-40T Güralp sensors may also be used to complete the data of the antenna. The source of LP events is located by using different approaches. In the first one, we used a method based on the measurement of the time delays between the early beginnings of LP events for each array receiver. The observed differences of time delays obtained for each pair of receivers are compared to theoretical values calculated from the travel times computed between grid nodes, which are positioned in the structure, and each receiver. In a second approach, we estimate the slowness vector by using MUSIC algorithm applied to 3-components data. From the slowness vector, we deduce the back-azimuth and the incident angle, which give an estimation of LP source depth in the conduit. This work is part of the Domerapi project funded by French Agence Nationale de la Recherche (https

  10. Location of Non-volcanic Tremors along the Cascadia Subduction Zone Using the Source- Scanning Algorithm

    NASA Astrophysics Data System (ADS)

    Farahbod, A.; Calvert, A.

    2009-05-01

    Due to the nature of Episodic Tremor and Slip (ETS) events, a long-term study and continuous seismic and geodetic data are required for a detailed study. Here we focus on tremors that occur along the Cascadia subduction zone between southern Vancouver Island and Northern California during slow slip events in two full-life cycles starting February 2003. The origin times and hypocenters of all tremors are estimated using the Source-Scanning Algorithm (SSA) of Kao (2004). We processed more than 200 days of continuously recorded seismic data from the US roughly the same amount of information extracted from the Canadian seismograms by compiling tremor catalogs provided by the Geological Survey of Canada (GSC) or by direct analysis of the waveforms. The majority of the well-located tremors in southern Vancouver Island, the Canada-US border region and northern Washington occur at a depth which ranges from 20 km to 40 km. In central and southern Washington, the depth of the well-located events gradually decreases with a westward shift of the epicenters towards the coast. Also both temporally and spatially it seems that tremors occur in locations with absent or sparse seismicity. In this study we will examine the geographical variability of ETS events as well as hypocentral migration rates and segmentation.

  11. Induced seismicity during the construction of the Gotthard Base Tunnel, Switzerland: hypocenter locations and source dimensions

    NASA Astrophysics Data System (ADS)

    Husen, Stephan; Kissling, Edi; von Deschwanden, Angela

    2013-01-01

    A series of 112 earthquakes was recorded between October 2005 and August 2007 during the excavation of the MFS Faido, the southernmost access point of the new Gotthard Base Tunnel. Earthquakes were recorded at a dense network of 11 stations, including 2 stations in the tunnel. Local magnitudes computed from Wood-Anderson-filtered horizontal component seismograms ranged from -1.0 to 2.4; the largest earthquake was strongly felt at the surface and caused considerable damage in the tunnel. Hypocenter locations obtained routinely using a regional 3-D P-wave velocity model and a constant Vp/Vs ratio 1.71 were about 2 km below the tunnel. The use of seismic velocities calibrated from a shot in the tunnel revealed that routinely obtained hypocenter locations were systematically biased to greater depth and are now relocated to be on the tunnel level. Relocation of the shot using these calibrated velocities yields a location accuracy of 25 m in longitude, 70 m in latitude, and 250 m in focal depth. Double-difference relative relocations of two clusters with highly similar waveforms showed a NW-SE striking trend that is consistent with the strike of mapped faults in the MFS Faido. Source dimensions computed using the quasidynamic model of Madariaga (Bull Seismo Soc Am 66(3):639-666, 1976) range from 50 to 170 m. Overlapping source dimensions for earthquakes within the two main clusters suggests that the same fault patch was ruptured repeatedly. The observed seismicity was likely caused by stress redistribution due to the excavation work in the MFS Faido.

  12. Induced seismicity during the construction of the Gotthard Base Tunnel, Switzerland: hypocenter locations and source dimensions

    NASA Astrophysics Data System (ADS)

    Husen, Stephan; Kissling, Edi; von Deschwanden, Angela

    2012-04-01

    A series of 112 earthquakes was recorded between October 2005 and August 2007 during the excavation of the MFS Faido, the southernmost access point of the new Gotthard Base Tunnel. Earthquakes were recorded at a dense network of 11 stations, including 2 stations in the tunnel. Local magnitudes computed from Wood-Anderson-filtered horizontal component seismograms ranged from -1.0 to 2.4; the largest earthquake was strongly felt at the surface and caused considerable damage in the tunnel. Hypocenter locations obtained routinely using a regional 3-D P-wave velocity model and a constant Vp/Vs ratio 1.71 were about 2 km below the tunnel. The use of seismic velocities calibrated from a shot in the tunnel revealed that routinely obtained hypocenter locations were systematically biased to greater depth and are now relocated to be on the tunnel level. Relocation of the shot using these calibrated velocities yields a location accuracy of 25 m in longitude, 70 m in latitude, and 250 m in focal depth. Double-difference relative relocations of two clusters with highly similar waveforms showed a NW-SE striking trend that is consistent with the strike of mapped faults in the MFS Faido. Source dimensions computed using the quasidynamic model of Madariaga (Bull Seismo Soc Am 66(3):639-666, 1976) range from 50 to 170 m. Overlapping source dimensions for earthquakes within the two main clusters suggests that the same fault patch was ruptured repeatedly. The observed seismicity was likely caused by stress redistribution due to the excavation work in the MFS Faido.

  13. Atmospheric Transport Modelling confining potential source location of East-Asian radionuclide detections in May 2010

    NASA Astrophysics Data System (ADS)

    Ross, J. Ole; Ceranna, Lars

    2016-04-01

    The radionuclide component of the International Monitoring System (IMS) to verify compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT) is in place to detect tiny traces of fission products from nuclear explosions in the atmosphere. The challenge for the interpretation of IMS radionuclide data is to discriminate radionuclide sources of CTBT relevance against emissions from nuclear facilities. Remarkable activity concentrations of Ba/La-140 occurred at the IMS radionuclide stations RN 37 (Okinawa) and RN 58 (Ussurysk) mid of May 2010. In those days also an elevated Xe-133 level was measured at RN 38 (Takasaki). Additional regional measurements of radioxenon were reported in the press and further analyzed in various publications. The radionuclide analysis gives evidence for the presence of a nuclear fission source between 10 and 12 May 2010. Backward Atmospheric Transport Modelling (ATM) with HYSPLIT driven by 0.2° ECMWF meteorological data for the IMS samples indicates that, assuming a single source, a wide range of source regions is possible including the Korean Peninsula, the Sea of Japan (East Sea), and parts of China and Russia. Further confinement of the possible source location can be provided by atmospheric backtracking for the assumed sampling periods of the reported regional xenon measurements. New studies indicate a very weak seismic event at the DPRK test site on early 12 May 2010. Forward ATM for a pulse release caused by this event shows fairly good agreement with the observed radionuclide signature. Nevertheless, the underlying nuclear fission scenario remains quite unclear and speculative even if assuming a connection between the waveform and the radionuclide event.

  14. Repetitive Long-Period Seismicity: Source Location and Mechanism Characteristics, Villarrica Volcano, Chile

    NASA Astrophysics Data System (ADS)

    Richardson, J.; Waite, G. P.

    2012-12-01

    Villarrica Volcano, Chile has an exposed magma free-surface, characterized by vigorous degassing ranging from small bubble bursts to Strombolian style slug bursting. Slug bursting events are characterized by both repetitive seismic and acoustic signals within the long-period (LP) band. We use the very repetitive nature of the low amplitude seismic LP signals to identify them with a matched filter on several persistent seismic stations, functional over the three year experiment duration. We stack the seismic and acoustic signals accompanying degassing to increase the signal to noise ratio, and tie signals measured 2010-2012 to produce a synthetic seismic network that recorded LP signals at a wide range of azimuths and distances from the source. Particle motions for most of the 21 stations were dominantly tangential, indicating the presence of a complex source geometry that deviated greatly from the logical axisymmetric geometry visible at the lave lake surface. We use the synthetic network to solve for the moment-tensor and location of the LP source, searching for the best source-time function using combinations of moment components, single force components, and both, for six different homogeneous half-space velocity models. Using the best source configuration and velocity model as a guide, we present forward models of reasonable geometries with geologic significance, including dikes, sills, pipes, and combination mechanisms to validate and test the sensitivity of the results of the free-inversion. Our results indicate that the current repetitive LP seismicity dominated by tangential particle motions is probably associated with relic fissure geometry from the last eruptive phase, and is caused by a conduit constriction through which large gas slugs pass (seismic emission) and subsequently burst at the surface (acoustic emission).

  15. Signatures of shock drivers in the solar wind and their dependence on the solar source location

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Cane, H. V.

    1993-01-01

    Solar wind and energetic ion observations following 40 interplanetary shocks with well-established solar source locations have been examined in order to determine whether signatures characteristic of the coronal material forming the shock driver are present. The signatures considered include magnetic-field-aligned bidirectional ion flows observed by the ISEE 3 and IMP 8 spacecraft; bidirectional solar wind electron heat fluxes; solar wind plasma proton and electron temperature depressions; low-beta plasma; enhanced, low-variance magnetic fields; and energetic ion depressions. Several shock driver signatures are commonly observed following shocks originating from within about 50 deg of central meridian, and are generally absent for other events. We conclude that shock drivers generally extend up to about 100 deg in longitude, centered on the solar source longitude. Since shocks from central meridian events are not usually associated with all the shock driver signatures examined, the absence of a driver cannot be confirmed from consideration of one of these signatures alone. We also find evidence that a few bidirectional energetic ion and solar wind electron heat flux events following shocks (in particular from far eastern sources) may occur on open field lines outside of shock drivers.

  16. Locating and estimating air emissions from sources of styrene. Interim report

    SciTech Connect

    Campbell, D.

    1991-10-01

    To assist groups interested in inventorying air emissions of various potentially toxic substances, EPA is preparing a series of documents such as this to compile available information on sources and emission of these substances. The document deals specifically with styrene. Its intended audience includes Federal, State and local air pollution personnel and others interested in locating potential emitters of styrene and in making gross estimates of air emissions therefrom. The document presents information on: (1) the types of sources that may emit styrene; (2) process variations and release points that may be emitted within these sources; and (3) available emissions information indicating the potential for styrene releases into the air from each operation. The document is being released as an interim document pending incorporation of testing results from the U.S. EPA. The EPA is currently testing several unsaturated polyester resin fabricators who produce cultured marble bathroom fixtures. When the test results are available, the EPA will publish a final report including these data.

  17. The impact of runoff generation mechanisms on the location of critical source areas

    USGS Publications Warehouse

    Lyon, S.W.; McHale, M.R.; Walter, M.T.; Steenhuis, T.S.

    2006-01-01

    Identifying phosphorus (P) source areas and transport pathways is a key step in decreasing P loading to natural water systems. This study compared the effects of two modeled runoff generation processes - saturation excess and infiltration excess - on total phosphorus (TP) and soluble reactive phosphorus (SRP) concentrations in 10 catchment streams of a Catskill mountain watershed in southeastern New York. The spatial distribution of runoff from forested land and agricultural land was generated for both runoff processes; results of both distributions were consistent with Soil Conservation Service-Curve Number (SCS-CN) theory. These spatial runoff distributions were then used to simulate stream concentrations of TP and SRP through a simple equation derived from an observed relation between P concentration and land use; empirical results indicate that TP and SRP concentrations increased with increasing percentage of agricultural land. Simulated TP and SRP stream concentrations predicted for the 10 catchments were strongly affected by the assumed runoff mechanism. The modeled TP and SRP concentrations produced by saturation excess distribution averaged 31 percent higher and 42 percent higher, respectively, than those produced by the infiltration excess distribution. Misrepresenting the primary runoff mechanism could not only produce erroneous concentrations, it could fail to correctly locate critical source areas for implementation of best management practices. Thus, identification of the primary runoff mechanism is critical in selection of appropriate models in the mitigation of nonpoint source pollution. Correct representation of runoff processes is also critical in the future development of biogeochemical transport models, especially those that address nutrient fluxes.

  18. Source contribution of PM₂.₅ at different locations on the Malaysian Peninsula.

    PubMed

    Ee-Ling, Ooi; Mustaffa, Nur Ili Hamizah; Amil, Norhaniza; Khan, Md Firoz; Latif, Mohd Talib

    2015-04-01

    This study determined the source contribution of PM2.5 (particulate matter <2.5 μm) in air at three locations on the Malaysian Peninsula. PM2.5 samples were collected using a high volume sampler equipped with quartz filters. Ion chromatography was used to determine the ionic composition of the samples and inductively coupled plasma mass spectrometry was used to determine the concentrations of heavy metals. Principal component analysis with multilinear regressions were used to identify the possible sources of PM2.5. The range of PM2.5 was between 10 ± 3 and 30 ± 7 µg m(-3). Sulfate (SO4 (2-)) was the major ionic compound detected and zinc was found to dominate the heavy metals. Source apportionment analysis revealed that motor vehicle and soil dust dominated the composition of PM2.5 in the urban area. Domestic waste combustion dominated in the suburban area, while biomass burning dominated in the rural area. PMID:25652682

  19. Accurate Multi-Phase Traveltimes in 2-D Layered Media Using a Fast Marching Scheme With Source Grid Refinement

    NASA Astrophysics Data System (ADS)

    Rawlinson, N.; Sambridge, M.

    2003-12-01

    The accurate prediction of seismic traveltimes in layered media is required in many areas of seismology. In addition to simple refractions and reflections, complex phases comprising numerous transmission and reflection branches may exist; for instance, the so-called ``multiples" frequently identified in marine reflection seismology. We present a grid-based method for the accurate determination of multi-phase traveltimes in layered media of significant complexity. A finite difference eikonal solver known as the Fast Marching Method (FMM) is used to track wavefronts within a layer. FMM is a fast and unconditionally stable upwind scheme that is well suited to complex models, and can be used sequentially to track the multiple refraction and/or reflection branches of virtually any required phase. Although FMM was initially introduced as a first-order scheme, higher order operators can be used. A mixed-order scheme that preferentially uses second-order operators, but reverts to first-order operators when the required upwind traveltimes are unavailable, is one possibility. Despite improved accuracy, this scheme still suffers from first-order convergence due to high wavefront curvature and first-order accuracy in the vicinity of the source. To overcome this problem, we implement local grid refinement about the source. In order to retain stability, the edge of the refined grid conforms to the shape of the wavefront, so that information only flows out of the refined grid, and never back into it. Application of our new scheme to complex velocity media shows that grid refinement typically improves accuracy by an order of magnitude, with only a small increase in computation time ( ˜5%). Significantly, first-order convergence is replaced by near second-order convergence, even in media with velocity contrasts as large as 8:1. In one example, with a velocity grid defined by 257,121 nodes, reflection traveltimes from a strongly undulating interface were calculated with an error of

  20. Location, Location, Location!

    ERIC Educational Resources Information Center

    Ramsdell, Kristin

    2004-01-01

    Of prime importance in real estate, location is also a key element in the appeal of romances. Popular geographic settings and historical periods sell, unpopular ones do not--not always with a logical explanation, as the author discovered when she conducted a survey on this topic last year. (Why, for example, are the French Revolution and the…

  1. Outbreaks source: A new mathematical approach to identify their possible location

    NASA Astrophysics Data System (ADS)

    Buscema, Massimo; Grossi, Enzo; Breda, Marco; Jefferson, Tom

    2009-11-01

    Classical epidemiology has generally relied on the description and explanation of the occurrence of infectious diseases in relation to time occurrence of events rather than to place of occurrence. In recent times, computer generated dot maps have facilitated the modeling of the spread of infectious epidemic diseases either with classical statistics approaches or with artificial “intelligent systems”. Few attempts, however, have been made so far to identify the origin of the epidemic spread rather than its evolution by mathematical topology methods. We report on the use of a new artificial intelligence method (the H-PST Algorithm) and we compare this new technique with other well known algorithms to identify the source of three examples of infectious disease outbreaks derived from literature. The H-PST algorithm is a new system able to project a distances matrix of points (events) into a bi-dimensional space, with the generation of a new point, named hidden unit. This new hidden unit deforms the original Euclidean space and transforms it into a new space (cognitive space). The cost function of this transformation is the minimization of the differences between the original distance matrix among the assigned points and the distance matrix of the same points projected into the bi-dimensional map (or any different set of constraints). For many reasons we will discuss, the position of the hidden unit shows to target the outbreak source in many epidemics much better than the other classic algorithms specifically targeted for this task. Compared with main algorithms known in the location theory, the hidden unit was within yards of the outbreak source in the first example (the 2007 epidemic of Chikungunya fever in Italy). The hidden unit was located in the river between the two village epicentres of the spread exactly where the index case was living. Equally in the second (the 1967 foot and mouth disease epidemic in England), and the third (1854 London Cholera epidemic

  2. Locating and Determining the Nature of a Persistent Hard X-Ray Source GROJ1814-12

    NASA Astrophysics Data System (ADS)

    Zhang, Shuang

    We propose to use RXTE in scanning mode to locate a persistent hard X-ray GROJ1814-12 near the Galactic plane, discovered by BATSE. Our location uncertainty is about 2 degrees in radius. Its flux level between 20-100 keV is around 30 mCrab. No flux variation is detectable by BATSE at time scales longer than a month. Candidate high energy sources within the error box are: unidentified variable EGRET source 2EG1813-12, X-ray burster 4U1812-12 and Z-source GX17+2. No persistent hard X-ray emision at this level is known from any class of the above sources. We also request a long exposure after the source is located, for a detailed spectral and timing study to determine its possible nature. Follow up ASCA observations will be proposed for a better location and X-ray spectroscopy.

  3. Stress Tolerance Variations in Saccharomyces cerevisiae Strains from Diverse Ecological Sources and Geographical Locations

    PubMed Central

    Zheng, Yan-Lin; Wang, Shi-An

    2015-01-01

    The budding yeast Saccharomyces cerevisiae is a platform organism for bioethanol production from various feedstocks and robust strains are desirable for efficient fermentation because yeast cells inevitably encounter stressors during the process. Recently, diverse S. cerevisiae lineages were identified, which provided novel resources for understanding stress tolerance variations and related shaping factors in the yeast. This study characterized the tolerance of diverse S. cerevisiae strains to the stressors of high ethanol concentrations, temperature shocks, and osmotic stress. The results showed that the isolates from human-associated environments overall presented a higher level of stress tolerance compared with those from forests spared anthropogenic influences. Statistical analyses indicated that the variations of stress tolerance were significantly correlated with both ecological sources and geographical locations of the strains. This study provides guidelines for selection of robust S. cerevisiae strains for bioethanol production from nature. PMID:26244846

  4. Experimentally determining the locations of two astigmatic images for an underwater light source

    NASA Astrophysics Data System (ADS)

    Yang, Pao-Keng; Liu, Jian-You; Ying, Shang-Ping

    2015-05-01

    Images formed by an underwater object from light rays refracted in the sagittal and tangential planes are located at different positions for an oblique viewing position. The overlapping of these two images from the observer's perspective will thus prevent the image-splitting astigmatism from being directly observable. In this work, we present a heuristic method to experimentally visualize the astigmatism. A point light source is used as an underwater object and the emerging wave front is recorded using a Shack-Hartmann wave-front sensor. The wave front is found to deform from a circular paraboloid to an elliptic paraboloid as the viewing position changes from normal to oblique. Using geometric optics, we derive an analytical expression for the image position as a function of the rotating angle of an arm used to carry the wave-front sensor in our experimental setup. The measured results are seen to be in good agreement with the theoretical predictions.

  5. Stress Tolerance Variations in Saccharomyces cerevisiae Strains from Diverse Ecological Sources and Geographical Locations.

    PubMed

    Zheng, Yan-Lin; Wang, Shi-An

    2015-01-01

    The budding yeast Saccharomyces cerevisiae is a platform organism for bioethanol production from various feedstocks and robust strains are desirable for efficient fermentation because yeast cells inevitably encounter stressors during the process. Recently, diverse S. cerevisiae lineages were identified, which provided novel resources for understanding stress tolerance variations and related shaping factors in the yeast. This study characterized the tolerance of diverse S. cerevisiae strains to the stressors of high ethanol concentrations, temperature shocks, and osmotic stress. The results showed that the isolates from human-associated environments overall presented a higher level of stress tolerance compared with those from forests spared anthropogenic influences. Statistical analyses indicated that the variations of stress tolerance were significantly correlated with both ecological sources and geographical locations of the strains. This study provides guidelines for selection of robust S. cerevisiae strains for bioethanol production from nature. PMID:26244846

  6. Automatic Infrasound Detection and Location of Sources in the western US

    NASA Astrophysics Data System (ADS)

    Park, J.; Arrowsmith, S.; Hayward, C.; Stump, B. W.

    2012-12-01

    Infrasound event catalogs can be used to study the characteristics of events as well as the time varying nature of the atmosphere. Additionally, these catalogs can be used to identify sources that repeat and thus provide ground truth for atmospheric studies. We focus on the production of a western US regional infrasound catalog for the time period of April 2011 to March 2012. Data from the University of Utah Seismograph Stations (UUSS) infrasonic arrays are supplemented with data from three additional infrasound arrays in Nevada. An automated detection procedure was applied to the observations based on an adaptive F-detector (Arrowsmith et al., 2009). The detection results document significant seasonal variations in time and space; detections during the winter tend to produce higher correlations relative to those from the summer, and a seasonal variation in azimuth is observed. These results indicate that the bulletin is seasonally variable. Association of detections and event localization was done utilizing the Bayesian infrasonic source location procedure (BISL, Modrak et al., 2010), accounting for unknown atmospheric propagation effects by adding a random component to the infrasonic group velocity. The resulting infrasonic catalog consists of 963 events for the one-year time period with indication of repeated events from a number of locations. The distribution of infrasound events in this study is well matched with the infrasound hot spots identified by Walker et al. (2011) which were based on a back projection procedure applied to seismic signals from USArray Transportable Array. There are common concentrations of events in both catalogs that include New Bomb in Nevada, Utah Test and Training Range (UTTR), and Dugway Proving Ground in Utah, as well as broader areas in central Nevada and southwest Idaho. The two bulletins document that the vast majority of events occur during work hours, suggesting they are related to human activities.

  7. Visibility of Type III burst source location as inferred from stereoscopic space observations

    NASA Astrophysics Data System (ADS)

    Boudjada, M. Y.; Galopeau, P. H. M.; Maksimovic, M.; Rucker, H. O.

    2014-11-01

    We study solar Type III radio bursts simultaneously observed by RPWS/Cassini, URAP/Ulysses and WAVES/Wind experiments. The observations allows us to cover a large frequency bandwidth from 16MHz down to a few kHz. We consider the onset time of each burst, and estimate the corresponding intensity level. Also we measure the Langmuir frequency as observed on the dynamic spectra recorded by the Ulysses spacecraft. The distances of Wind, Ulysses and Cassini spacecraft, with regard to the Sun, were in the order of 1AU, 2.4AU and 4.5AU, respectively. The spacecraft trajectories were localized in the ecliptic plane in the case of Wind and Cassini, and for Ulysses in the southern hemisphere (i.e. heliocentric latitude higher than -50). Despite the different locations, the spectral patterns of the selected solar bursts are found to be similar between 10MHz and 2MHz but unalike at lower frequency. We discuss the variation of the intensity level as recorded by the three spacecraft. We show that the reception system of each experiment affected the way the Type III burst intensity is measured. Also we attempt to estimate the electron beam along the interplanetary magnetic field where the trajectory is an Archimedean spiral. This leads us to infer on the visibility of the source location with regard to the spacecraft position.

  8. Explosion Source Location Study Using Collocated Acoustic and Seismic Networks in Israel

    NASA Astrophysics Data System (ADS)

    Pinsky, V.; Gitterman, Y.; Arrowsmith, S.; Ben-Horin, Y.

    2013-12-01

    infrasonic phases of the two distant arrays; 2) a standard robust grid-search location procedure based on phase picks and a constant celerity for a phase (tropospheric or stratospheric) was applied; 3) a joint coordinate grid-search procedure using array waveforms and phase picks was tested, 4) the Bayesian Infrasonic Source Localization (BISL) method, incorporating semi-empirical model-based prior information, was modified for array+network configuration and applied to the ground-truth events. For this purpose we accumulated data of the former observations of the air-to-ground infrasonic phases to compute station specific ground-truth Celerity-Range Histograms (ssgtCRH) and/or model-based CRH (mbCRH), which allow to essentially improve the location results. For building the mbCRH the local meteo-data and the ray-tracing modeling in 3 available azimuth ranges, accounting seasonal variations of winds directivity (quadrants North:315-45, South: 135-225, East 45-135) have been used.

  9. Site Characterization of the Source Physics Experiment Phase II Location Using Seismic Reflection Data

    NASA Astrophysics Data System (ADS)

    Sexton, E. A.; Snelson, C. M.; Chipman, V.; Emer, D. F.; White, R. L.; Emmitt, R.; Wright, A. A.; Drellack, S.; Huckins-Gang, H.; Mercadante, J.; Floyd, M.; McGowin, C.; Cothrun, C.; Bonal, N.

    2013-12-01

    An objective of the Source Physics Experiment (SPE) is to identify low-yield nuclear explosions from a regional distance. Low-yield nuclear explosions can often be difficult to discriminate among the clutter of natural and man-made explosive events (e.g., earthquakes and mine blasts). The SPE is broken into three phases. Phase I has provided the first of the physics-based data to test the empirical models that have been used to discriminate nuclear events. The Phase I series of tests were placed within a highly fractured granite body. The evolution of the project has led to development of Phase II, to be placed within the opposite end member of geology, an alluvium environment, thereby increasing the database of waveforms to build upon in the discrimination models. Both the granite and alluvium sites have hosted nearby nuclear tests, which provide comparisons for the chemical test data. Phase III of the SPE is yet to be determined. For Phase II of the experiment, characterization of the location is required to develop the geologic/geophysical models for the execution of the experiment. Criteria for the location are alluvium thickness of approximately 170 m and a water table below 170 m; minimal fracturing would be ideal. A P-wave mini-vibroseis survey was conducted at a potential site in alluvium to map out the subsurface geology. The seismic reflection profile consisted of 168 geophone stations, spaced 5 m apart. The mini-vibe was a 7,000-lb peak-force source, starting 57.5 m off the north end of the profile and ending 57.5 m past the southern-most geophone. The length of the profile was 835 m. The source points were placed every 5 m, equally spaced between geophones to reduce clipping. The vibroseis sweep was from 20 Hz down to 180 Hz over 8 seconds, and four sweeps were stacked at each shot location. The shot gathers show high signal-to-noise ratios with clear first arrivals across the entire spread and the suggestion of some shallow reflectors. The data were

  10. Locating ignimbrite source using volcanologic and magnetic proxies: the Afyon-Eskisehir case study (Western Anatolia)

    NASA Astrophysics Data System (ADS)

    Agrò, Alessandro; Zanella, Elena; Le Pennec, Jean-Luc; Temel, Abidin

    2013-04-01

    This study exploits volcanologic and magnetic techniques to the investigation of the Early-Middle Miocene pyroclastic sequence exposed in the ~120 x 80 km area comprised between the cities of Eskisehir to the North and Afyon to the South (Western Anatolia), in order to locate the source by combining flow directions inferred by field analysis (clasts embrication and sedimentary structures) and those obtained by the analysis of magnetic fabric on the ignimbrite deposits (anisotropy of magnetic susceptibility, AMS, and anisotropy of remanent magnetization, ARM). Moreover we integrated directional flow data with preliminary isopleth and isopach maps of the air-fall deposits. The sequence belongs to the most important magmatic activity in the region, named Kırka-Afyon-Isparta Volcanism (KAIV), which originated a calc-alkaline pyroclastic sequence intercalated with some lava and breccias, and the products of an effusive activity with alkaline affinities lasted until Quaternary times. Stratigraphy points out to the presence of two main eruptive events which originated several ignimbrite units distinguished on the basis of macroscopic features (mineralogy and texture) and areal distribution of the deposits; the overall areal extension and volume of the pyroclastic products is ~8,000 km2 and ~200 km3. The oldest event generated the Akcakaya ignimbrites, which are exposed in the Northern part of the area; lacustrine sedimentary deposits separate them from the younger Demirli ignimbrites, cropping out in the Southern part of the area; both the Akcakaya and Demirli ignimbrites are overlain by lava sheets. Magnetic sampling has been carried out at 20 areal distributed localities in the two ignimbrite deposits (30 sites, 600 specimens); each section was sampled from 1 to 3 sites at different stratigraphic height. Rock magnetic measurements point out to the presence of Ti-magnetite as the main magnetic carrier. At some localities AMS fabric is vertically consistent through the

  11. Tracking the MSL-SAM methane detection source location Through Mars Regional Atmospheric Modeling System (MRAMS)

    NASA Astrophysics Data System (ADS)

    Pla-García, Jorge

    2016-04-01

    1. Introduction: The putative in situ detection of methane by Sample Analysis at Mars (SAM) instrument suite on Curiosi-ty at Gale crater has garnered significant attention because of the potential implications for the presence of geological methane sources or indigenous Martian organisms [1, 2]. SAM reported detection of back-ground levels of atmospheric methane of mean value 0.69±0.25 parts per billion by volume (ppbv) at the 95% confidence interval (CI). Additionally, in four sequential measurements spanning a 60-sol period, SAM observed elevated levels of methane of 7.2±2.1 ppbv (95% CI), implying that Mars is episodically producing methane from an additional unknown source. There are many major unresolved questions regard-ing this detection: 1) What are the potential sources of the methane release? 2) What causes the rapid decrease in concentration? and 3) Where is the re-lease location? 4) How spatially extensive is the re-lease? 5) For how long is CH4 released? Regarding the first question, the source of methane, is so far not identified. It could be related with geo-logical process like methane release from clathrates [3], serpentinisation [4] and volcanism [5]; or due to biological activity from methanogenesis [6]. To answer the second question, the rapid decrease in concentration, it is important to note that the photo-chemical lifetime of methane is of order 100 years, much longer than the atmospheric mixing time scale, and thus the gas should tend to be well mixed except near a source or shortly after an episodic release. The observed spike of 7 ppb from the background of <1 ppb, and then the rapid return to the background lev-el could be due to a sink (destruction) or due to at-mospheric mixing. A wind mediated erosion process of ordinary quartz crystals was proposed to produce activated quartz grains, which sequester methane by forming covalent Si-C bonds. If this process is op-erational on Mars today, which some recent prelimi-nary studies on

  12. A Review of Advancements in Particulate Matter Sampling and Analysis and its Application to Identifying Source Impacts at Receptor Locations

    EPA Science Inventory

    Time-integrated (typically 24-hr) filter-based methods (historical methods) form the underpinning of our understanding of the fate, impact of source emissions at receptor locations (source impacts), and potential health and welfare effects of particulate matter (PM) in air. Over...

  13. System for locating the sources of wideband dE/dt from lightning

    NASA Technical Reports Server (NTRS)

    Thomson, E. M.; Medelius, P. J.; Davis, S.

    1994-01-01

    A system has been developed to measure wideband electic field derivatives (dE/dt) at five ground stations in a 15 km x 15 km network at Kennedy Space Center. Individual station responses are normalized using digital filters. Pulse-timing resolution is improved to much less than 50-ns sample interval by interpolation using packing in the frequency domain. A time tag for each pulse is defined as the mean of the times of the rising-edge half peak, peak, and falling-edge half peak. The standard deviation in these times defines the timing error and is shown to be a function of noise and bandwidth rather than digitization rate. Each of the four unknowns for a pulse source location (x,y,z) and time of occurrence (t) is found from the five time-tag measurements using different weightings for all five combinations of the four-station hyperbolic equations. Weighting factors and errors in x,y,z and t are estimated using error propagation techniques.

  14. How drone flies (Eristalis tenax L., Syrphidae, Diptera) use floral guides to locate food sources.

    PubMed

    Dinkel, T; Lunau, K

    2001-09-01

    In this study we show how inexperienced syrphid flies, Eristalis tenax, orient on artificial flowers by means of floral guides. To test the effect of floral guides such as line and ring markings on the probability and speed of the location of a potential food source, we exploited the spontaneous proboscis reaction triggered by yellow colour stimuli. We tested whether and how fast the flies, when placed on the edge of a circular dummy flower, found a small central yellow spot and touched it with the proboscis extended. The flies found the central yellow spot more often and faster if guide lines from the margin to the yellow spot were present. The effect of guide lines was dependent on the colour of the dummy flower, and independent of the colour of the guide lines, except for yellow guide lines releasing the proboscis reaction. The effect of guide lines was stronger if the yellow spot was hidden in a 2 mm deep depression and thus not as easily visible to the flies. Ring guides had a significant effect on performance only when the intensity of the central yellow spot was low. PMID:12770188

  15. Locating pollutant emission sources with optical remote sensing measurements and an improved one-dimensional radial plume mapping technique.

    PubMed

    Wu, Chang-fu; Lin, Shih-Chun; Yeh, Cheng-Kai

    2012-04-01

    Previous studies have shown that there was a relatively large amount of uncertainty along the major wind direction in the results of locating emission sources using the one-dimensional radial plume mapping (RPM(1D)) technique based on optical remote sensing measurements. This paper proposes setting up an additional monitoring line that is perpendicular to the original scanning beam geometry to reduce this uncertainty. We first conducted a computer simulation study using the Gaussian dispersion model to generate the downwind concentrations of plumes from 400 source locations in a 201 m × 201 m spatial domain under various wind directions (n = 181). The optical remote sensing instrument was assumed to be at (0, 0) with two perpendicular monitoring lines, each of which had three beam segments of equal length. Each pair of the reconstructed downwind concentration profiles was then used to trace back to the source locations. The results showed that the accuracy of the method and its uncertainty were improved by using the proposed two-line RPM(1D) approach rather than the original one-line RPM(1D) approach at most simulated source locations. In a follow-up field experiment, a tracer gas was released at the coordinate of (100, 100). The release location was covered within the 0.25- to 0.5-probability area of the estimated results, and the distance between the actual and estimated source locations was 18.4 m (9.2% of the longest beam path). PMID:22382995

  16. Locating non-volcanic tremor along the San Andreas Fault using a multiple array source imaging technique

    USGS Publications Warehouse

    Ryberg, T.; Haberland, C.H.; Fuis, G.S.; Ellsworth, W.L.; Shelly, D.R.

    2010-01-01

    Non-volcanic tremor (NVT) has been observed at several subduction zones and at the San Andreas Fault (SAF). Tremor locations are commonly derived by cross-correlating envelope-transformed seismic traces in combination with source-scanning techniques. Recently, they have also been located by using relative relocations with master events, that is low-frequency earthquakes that are part of the tremor; locations are derived by conventional traveltime-based methods. Here we present a method to locate the sources of NVT using an imaging approach for multiple array data. The performance of the method is checked with synthetic tests and the relocation of earthquakes. We also applied the method to tremor occurring near Cholame, California. A set of small-aperture arrays (i.e. an array consisting of arrays) installed around Cholame provided the data set for this study. We observed several tremor episodes and located tremor sources in the vicinity of SAF. During individual tremor episodes, we observed a systematic change of source location, indicating rapid migration of the tremor source along SAF. ?? 2010 The Authors Geophysical Journal International ?? 2010 RAS.

  17. Location of the Norma transient with the HEAO 1 scanning modulation collimator. [X ray source in Norma Constellation

    NASA Technical Reports Server (NTRS)

    Fabbiano, G.; Gursky, H.; Schwartz, D. A.; Schwarz, J.; Bradt, H. V.; Doxsey, R. E.

    1978-01-01

    A precise position has been obtained for an X-ray transient source in Norma. The location uncertainty includes a variable star previously suggested to be the optical counterpart. This transient is associated with the steady X-ray source MX 1608-52 and probably with an X-ray burst source. A binary system containing a low-mass primary and a neutron-star or black-hole secondary of a few solar masses is consistent with the observations.

  18. Producing Accurate Stereographic Images with a Flashlight and Layers of Glass: A Source for Stereopsis via Slides or Overhead Projection.

    ERIC Educational Resources Information Center

    Strauss, Michael J.; Levine, Shellie H.

    1985-01-01

    Describes an extremely simple technique (using only Dreiding or Framework molecular models, a flashlight, small sheets of glass, and a piece of cardboard) which produces extremely accurate line drawings of stereoscopic images. Advantages of using the system are noted. (JN)

  19. The Role of Color Cues in Facilitating Accurate and Rapid Location of Aided Symbols by Children with and without Down Syndrome

    ERIC Educational Resources Information Center

    Wilkinson, Krista; Carlin, Michael; Thistle, Jennifer

    2008-01-01

    Purpose: This research examined how the color distribution of symbols within a visual aided augmentative and alternative communication array influenced the speed and accuracy with which participants with and without Down syndrome located a target picture symbol. Method: Eight typically developing children below the age of 4 years, 8 typically…

  20. Characterization and applications of VLF/LF source locations from lightning using the Huntsville Alabama Marx Meter Array

    NASA Astrophysics Data System (ADS)

    Bitzer, Phillip M.; Christian, Hugh J.; Stewart, Mike; Burchfield, Jeff; Podgorny, Scott; Corredor, David; Hall, John; Kuznetsov, Evgeny; Franklin, Veronica

    2013-04-01

    Arrays that detect and locate the four-dimensional spacetime positions of radiation sources from lightning have largely utilized sensors sensitive to the very high frequency (VHF) regime with ˜ 15 km baselines or very low frequency/low frequency (VLF/LF) regime with ˜ 100 km baselines. This paper details initial results from the newly developed Huntsville Alabama Marx Meter Array (HAMMA), consisting of Marx meters (electric field change meters) sensitive to a frequency band ˜ 1 Hz to 400 kHz. The arrival time of HAMMA waveforms due to radiation sources from lightning are used to determine the spacetime position of these sources. The locations are compared with two well-documented and operational arrays, the National Lightning Detection Network (NLDN) and the North Alabama Lightning Mapping Array (NALMA). The standard deviation of the difference between HAMMA and NLDN locations of return strokes is 305 and 266 m in x and y, respectively, while the standard deviation of the difference between HAMMA and NALMA sources is 237, 226, and 688 m in x, y and z, respectively. We further show that NLDN intracloud locations differ in horizontal distance from the corresponding HAMMA locations by a median value of 479 m. In addition, we use HAMMA source locations to map several lightning flashes in the VLF/LF and show HAMMA sources largely map out the same electrical extent as VHF sources and provide unique insights to the properties of the discharges occurring. Finally, we show that VLF/LF sources can determine the leader polarity in several example flashes but not necessarily whether a flash comes to ground. Copyright 2013 American Geophysical Union. All rights reserved.

  1. Tracking the MSL-SAM methane detection source location Through Mars Regional Atmospheric Modeling System (MRAMS)

    NASA Astrophysics Data System (ADS)

    Pla-García, Jorge

    2016-04-01

    1. Introduction: The putative in situ detection of methane by Sample Analysis at Mars (SAM) instrument suite on Curiosi-ty at Gale crater has garnered significant attention because of the potential implications for the presence of geological methane sources or indigenous Martian organisms [1, 2]. SAM reported detection of back-ground levels of atmospheric methane of mean value 0.69±0.25 parts per billion by volume (ppbv) at the 95% confidence interval (CI). Additionally, in four sequential measurements spanning a 60-sol period, SAM observed elevated levels of methane of 7.2±2.1 ppbv (95% CI), implying that Mars is episodically producing methane from an additional unknown source. There are many major unresolved questions regard-ing this detection: 1) What are the potential sources of the methane release? 2) What causes the rapid decrease in concentration? and 3) Where is the re-lease location? 4) How spatially extensive is the re-lease? 5) For how long is CH4 released? Regarding the first question, the source of methane, is so far not identified. It could be related with geo-logical process like methane release from clathrates [3], serpentinisation [4] and volcanism [5]; or due to biological activity from methanogenesis [6]. To answer the second question, the rapid decrease in concentration, it is important to note that the photo-chemical lifetime of methane is of order 100 years, much longer than the atmospheric mixing time scale, and thus the gas should tend to be well mixed except near a source or shortly after an episodic release. The observed spike of 7 ppb from the background of <1 ppb, and then the rapid return to the background lev-el could be due to a sink (destruction) or due to at-mospheric mixing. A wind mediated erosion process of ordinary quartz crystals was proposed to produce activated quartz grains, which sequester methane by forming covalent Si-C bonds. If this process is op-erational on Mars today, which some recent prelimi-nary studies on

  2. Source amplitudes of volcano-seismic signals determined by the amplitude source location method as a quantitative measure of event size

    NASA Astrophysics Data System (ADS)

    Kumagai, Hiroyuki; Lacson, Rudy; Maeda, Yuta; Figueroa, Melquiades S.; Yamashina, Tadashi; Ruiz, Mario; Palacios, Pablo; Ortiz, Hugo; Yepes, Hugo

    2013-05-01

    The amplitude source location (ASL) method, which uses high-frequency amplitudes under the assumption of isotropic S-wave radiation, has been shown to be useful for locating the sources of various types of volcano-seismic signals. We tested the ASL method by using synthetic seismograms and examined the source amplitudes determined by this method for various types of volcano-seismic signals observed at different volcanoes. Our synthetic tests indicated that, although ASL results are not strongly influenced by velocity structure and noise, they do depend on site amplification factors at individual stations. We first applied the ASL method to volcano-tectonic (VT) earthquakes at Taal volcano, Philippines. Our ASL results for the largest VT earthquake showed that a frequency range of 7-12 Hz and a Q value of 50 were appropriate for the source location determination. Using these values, we systematically estimated source locations and amplitudes of VT earthquakes at Taal. We next applied the ASL method to long-period events at Cotopaxi volcano and to explosions at Tungurahua volcano in Ecuador. We proposed a practical approach to minimize the effects of site amplifications among different volcano seismic networks, and compared the source amplitudes of these various volcano-seismic events with their seismic magnitudes. We found a proportional relation between seismic magnitude and the logarithm of the source amplitude. The ASL method can be used to determine source locations of small events for which onset measurements are difficult, and thus can estimate the sizes of events over a wider range of sizes compared with conventional hypocenter determination approaches. Previously, there has been no parameter widely used to quantify the sources of volcano-seismic signals. This study showed that the source amplitude determined by the ASL method may be a useful quantitative measure of volcano-seismic event size.

  3. Nature and location of the source of plasma sheet boundary layer ion beams

    NASA Astrophysics Data System (ADS)

    Elphic, R. C.; Onsager, T. G.; Thomsen, M. F.; Gosling, J. T.

    1995-02-01

    Onsager et al. (1991) have put forward a model of the formation of the plasma sheet boundary layer (PSBL) which relies on a steady source of plasma from a spatially extended plasma sheet, together with steady equatorward and earthward ExB convection of field lines due to reconnection at a downtail neutral line. This model is a synthesis of earlier proposals and it explains such features as an electron layer exterior to the ion boundary layer, ion velocity dispersion, counter streaming beams, low-speed cutoffs in the beams. It also explains the apparent evolution of the ion beams through 'kidney bean' shaped velocity-space distributions toward quasi-isotropic shells without invoking pitch angle scattering or energy diffusion. In this paper we explore two ramifications of the model. In principle we can map, as a function of time, the downtail neutral line distance and establish whether or not it is retreating during substorm recovery. We can also reconstruct the plasma distribution function near the neutral line to see if it is most consistent with mantle or plasma sheet plasma. We perform this analysis using International Sun Earth Explorer (ISEE) Fast Plasma Experiment (FPE) data for two plasma sheet recovery events, one on March 1, 1978, and the other on April 18, 1978. On March 1, 1978, we find evidence for an initial retreat from around 110 to 160 R(sub E) in the first 15 min; little further retreat occurs thereafter. On April 18, 1978, the neutral line location ranges from as little as 40 R(sub E) tailward of the satellite to as much as 200 R(sub E), but there is no evidence for a systematic retreat. The reconstructed ion distributions for these events are most consistent with a plasma sheet origin for the March 1 case and possibly plasma mantle or low-latitude boundary layer for the April 18 case.

  4. Surveillance of nasal and bladder cancer to locate sources of exposure to occupational carcinogens.

    PubMed Central

    Teschke, K; Morgan, M S; Checkoway, H; Franklin, G; Spinelli, J J; van Belle, G; Weiss, N S

    1997-01-01

    OBJECTIVE: To locate sources of occupational exposure to nasal and bladder carcinogens for surveillance follow up in British Columbia, Canada. METHODS: Incident cases of nasal cancer (n = 48), bladder cancer (n = 105), and population based controls (n = 159) matched for sex and age, were interviewed about their jobs, exposures, and smoking histories. Odds ratios (ORs) were calculated for 57 occupational groups with stratified exact methods to control for age, sex, and smoking. RESULTS: Occupational groups at increased risk of nasal cancer included: textile workers (six cases, OR 7.6); miners, drillers, and blasters (six cases, OR 3.5); welders (two cases, OR 3.5); pulp and paper workers (three cases, OR 3.1); and plumbers and pipefitters (two cases, OR 3.0). Nasal cancer ORs were not increased in occupations exposed to wood dust, possibly due to low exposures in local wood industries. Strongly increased risks of bladder cancer were found for sheet metal workers (four cases, OR 5.3), miners (19 cases, OR 4.5), gardeners (six cases, OR 3.7), and hairdressers (three cases, OR 3.2). Among occupations originally considered at risk, the following had increased risks of bladder cancer: painters (four cases, OR 2.8); laundry workers (five cases, OR 2.3); chemical and petroleum workers (15 cases, OR 1.8); machinists (eight cases, OR 1.6); and textile workers (three cases, OR 1.5). CONCLUSIONS: Occupational groups with increased risks and three or more cases with similar duties were selected for surveillance follow up. For nasal cancer, these included textile workers (five were garment makers) and pulp and paper workers (three performed maintenance tasks likely to entail stainless steel welding). For bladder cancer, these included miners (12 worked underground), machinists (five worked in traditional machining), hairdressers (three had applied hair dyes), and laundry workers (three were drycleaners). PMID:9245952

  5. Acoustic emission source location and damage detection in a metallic structure using a graph-theory-based geodesic approach

    NASA Astrophysics Data System (ADS)

    Gangadharan, R.; Prasanna, G.; Bhat, M. R.; Murthy, C. R. L.; Gopalakrishnan, S.

    2009-11-01

    A geodesic-based approach using Lamb waves is proposed to locate the acoustic emission (AE) source and damage in an isotropic metallic structure. In the case of the AE (passive) technique, the elastic waves take the shortest path from the source to the sensor array distributed in the structure. The geodesics are computed on the meshed surface of the structure using graph theory based on Dijkstra's algorithm. By propagating the waves in reverse virtually from these sensors along the geodesic path and by locating the first intersection point of these waves, one can get the AE source location. The same approach is extended for detection of damage in a structure. The wave response matrix of the given sensor configuration for the healthy and the damaged structure is obtained experimentally. The healthy and damage response matrix is compared and their difference gives the information about the reflection of waves from the damage. These waves are backpropagated from the sensors and the above method is used to locate the damage by finding the point where intersection of geodesics occurs. In this work, the geodesic approach is shown to be suitable to obtain a practicable source location solution in a more general set-up on any arbitrary surface containing finite discontinuities. Experiments were conducted on aluminum specimens of simple and complex geometry to validate this new method.

  6. Efficient yet accurate solution of the linear transport equation in the presence of internal sources - The exponential-linear-in-depth approximation

    NASA Technical Reports Server (NTRS)

    Kylling, Arve; Stamnes, Knut

    1992-01-01

    The present solutions to the linear transport equation pertain to monoenergetic particles' interaction with a multiple scattering/absorbing layered medium with a general anisotropic internal source term. Attention is given to a novel exponential-linear approximation to the internal source, as a function of scattering depth, which furnishes an at-once efficient and accurate solution to the linear transport equation through its reduction of the spatial mesh size. The great superiority of the proposed method is demonstrated by the numerical results obtained in the illustrative cases of (1) an embedded thermal source and (2) a rapidly varying beam pseudosource.

  7. Acoustic source location in the secondary mixing region of a jet-blown flap using a cross-correlation technique

    NASA Technical Reports Server (NTRS)

    Becker, R. S.; Maus, J. R.

    1977-01-01

    An experimental investigation of the acoustic sources in the secondary mixing region of a laboratory-scale jet-flap was made using a causality correlation technique. The processed signal of a hot-film anemometer probe was cross correlated with the output signal of a far-field microphone. Axial acoustic source strength distributions were measured for three far-field microphone locations: plus or minus 45 deg in the flyover plane and 45 deg in the sideline plane. These measurements showed that the acoustic sources in the secondary mixing region are highly directional, radiating much more effectively to the -45 deg-microphone, located below the plane of the flap surface. A relative maximum in the acoustic source strength measured for the microphones in the flyover plane occurred very near the flap trailing edge, which may be due to an edge amplification effect predicted by the theoretical work of Ffowcs Williams and Hall.

  8. Estimation of source location and ground impedance using a hybrid multiple signal classification and Levenberg-Marquardt approach

    NASA Astrophysics Data System (ADS)

    Tam, Kai-Chung; Lau, Siu-Kit; Tang, Shiu-Keung

    2016-07-01

    A microphone array signal processing method for locating a stationary point source over a locally reactive ground and for estimating ground impedance is examined in detail in the present study. A non-linear least square approach using the Levenberg-Marquardt method is proposed to overcome the problem of unknown ground impedance. The multiple signal classification method (MUSIC) is used to give the initial estimation of the source location, while the technique of forward backward spatial smoothing is adopted as a pre-processer of the source localization to minimize the effects of source coherence. The accuracy and robustness of the proposed signal processing method are examined. Results show that source localization in the horizontal direction by MUSIC is satisfactory. However, source coherence reduces drastically the accuracy in estimating the source height. The further application of Levenberg-Marquardt method with the results from MUSIC as the initial inputs improves significantly the accuracy of source height estimation. The present proposed method provides effective and robust estimation of the ground surface impedance.

  9. Wide aperture arrays for locating impulsive sound sources in air and underwater

    NASA Astrophysics Data System (ADS)

    Ferguson, Brian G.

    2006-05-01

    Passive ranging techniques are used in land-based acoustic surveillance systems and underwater sonar systems to localize sources that radiate acoustic energy into the environment. Passive ranging by wavefront curvature relies on the spherical expansion of the wavefronts as the acoustic energy propagates outwards from the source. A wide-aperture receiving array is used to sense the curvature of the wavefront by estimating the intersensor time delays as the wavefront traverses the array. The time delay estimates are used to calculate the range (which is equal to the radius of curvature of the wavefront) and bearing of the source. The wavefront curvature method is applied here to the passive ranging of sources of four different types of acoustic signals: underwater mechanical transients, underwater biological transients, continuous sound wave transmissions in air and impulsive sounds in air. The method provides precise range and bearing estimates of underwater signal sources. In comparison, large passive ranging errors are observed for in-air sources because the atmosphere is a nonstationary sound propagation medium. Atmospheric turbulence causes perturbations in the curvature of the acoustic wavefronts and leads to random fluctuations in the source position estimates on time scales ranging from seconds to minutes. Background noise at each sensor has only a small effect on the positional uncertainty of in-air sources with random fluctuations in the source position estimates occurring on subsecond time scales.

  10. The effect of contaminant source location on worker exposure in the near-wake region.

    PubMed

    Kulmala, I; Säämänen, A; Enbom, S

    1996-10-01

    The exposure of workers in the near-wake region due to a recirculating airflow was studied experimentally and numerically. A mannequin was installed in an open-ended tunnel and tracer gas was released at several locations downstream to determine the size and location of the reverse flow region. The contaminant transport into the breathing zone was found to depend strongly on the location of the release point. The airflow field was also determined numerically assuming a steady flow and using the standard k-epsilon turbulence model. After calculating the turbulent airflow field, a large number of submicrometre particles were released in different locations downstream of the mannequin to simulate the transport of gaseous contaminants. Although this method does not provide actual exposures, it does predict the tendencies in exposure variations due to different release points quite satisfactorily. PMID:8888634

  11. Source apportionment and location by selective wind sampling and Positive Matrix Factorization.

    PubMed

    Venturini, Elisa; Vassura, Ivano; Raffo, Simona; Ferroni, Laura; Bernardi, Elena; Passarini, Fabrizio

    2014-10-01

    In order to determine the pollution sources in a suburban area and identify the main direction of their origin, PM2.5 was collected with samplers coupled with a wind select sensor and then subjected to Positive Matrix Factorization (PMF) analysis. In each sample, soluble ions, organic carbon, elemental carbon, levoglucosan, metals, and Polycyclic Aromatic Hydrocarbons (PAHs) were determined. PMF results identified six main sources affecting the area: natural gas home appliances, motor vehicles, regional transport, biomass combustion, manufacturing activities, and secondary aerosol. The connection of factor temporal trends with other parameters (i.e., temperature, PM2.5 concentration, and photochemical processes) confirms factor attributions. PMF analysis indicated that the main source of PM2.5 in the area is secondary aerosol. This should be mainly due to regional contributions, owing to both the secondary nature of the source itself and the higher concentration registered in inland air masses. The motor vehicle emission source contribution is also important. This source likely has a prevalent local origin. The most toxic determined components, i.e., PAHs, Cd, Pb, and Ni, are mainly due to vehicular traffic. Even if this is not the main source in the study area, it is the one of greatest concern. The application of PMF analysis to PM2.5 collected with this new sampling technique made it possible to obtain more detailed results on the sources affecting the area compared to a classical PMF analysis. PMID:24488520

  12. Efficient Location of Research Reference Sources in the Field of Dance.

    ERIC Educational Resources Information Center

    Kissinger, Pat; Jay, Danielle

    More than 45 basic dance reference research sources that would be useful to students, scholars, teachers, historians, and therapists are discussed in this bibliographic essay. Aspects of dance covered include choreography, criticism, teaching principles, aesthetic theory, dance therapy, and history. Sources are grouped by type: dictionaries and…

  13. Locating and estimating air emissions from sources of lead and lead compounds

    SciTech Connect

    1998-05-01

    This document describes the properties of lead and lead compounds as air pollutants, defines their production and use patterns, identifies source categories of air emissions, and provides lead emission factors. Lead is primarily used in the manufacture of lead-acid batteries, lead alloys, lead oxides in pigments, glass, lead cable coating, and a variety of lead products including ammunition and radiation shielding. Lead is emitted into the atmosphere from mining and smelting; from its use as feedstock in the production of lead alloys, lead compounds and other lead-containing products; from mobile sources; and from combustion sources. In addition to the lead and lead compound sources and emission factor data, information is provided that specifies how individual sources of lead and lead compounds may be tested to quantify air emissions.

  14. 40 CFR 55.14 - Requirements that apply to OCS sources located within 25 miles of States' seaward boundaries, by...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Requirements that apply to OCS sources located within 25 miles of States' seaward boundaries, by State. 55.14 Section 55.14 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) OUTER CONTINENTAL SHELF AIR REGULATIONS § 55.14 Requirements...

  15. Algorithms for locating celestial sources of X-rays and gamma flares with the aid of several spacecraft

    NASA Technical Reports Server (NTRS)

    Mersov, G. A.

    1979-01-01

    An Algorithm is suggested for defining the coordinates of X-ray and Gamma Ray radiation sources by measuring the time lag of the transmission of radiation flares from various points of space in which spacecraft are located. Instances are cited where the 2-x, 3-x and 4x spacecraft are used.

  16. Locating Sensors for Detecting Source-to-Target Patterns of Special Nuclear Material Smuggling: A Spatial Information Theoretic Approach

    PubMed Central

    Przybyla, Jay; Taylor, Jeffrey; Zhou, Xuesong

    2010-01-01

    In this paper, a spatial information-theoretic model is proposed to locate sensors for detecting source-to-target patterns of special nuclear material (SNM) smuggling. In order to ship the nuclear materials from a source location with SNM production to a target city, the smugglers must employ global and domestic logistics systems. This paper focuses on locating a limited set of fixed and mobile radiation sensors in a transportation network, with the intent to maximize the expected information gain and minimize the estimation error for the subsequent nuclear material detection stage. A Kalman filtering-based framework is adapted to assist the decision-maker in quantifying the network-wide information gain and SNM flow estimation accuracy. PMID:22163641

  17. Locating sensors for detecting source-to-target patterns of special nuclear material smuggling: a spatial information theoretic approach.

    PubMed

    Przybyla, Jay; Taylor, Jeffrey; Zhou, Xuesong

    2010-01-01

    In this paper, a spatial information-theoretic model is proposed to locate sensors for detecting source-to-target patterns of special nuclear material (SNM) smuggling. In order to ship the nuclear materials from a source location with SNM production to a target city, the smugglers must employ global and domestic logistics systems. This paper focuses on locating a limited set of fixed and mobile radiation sensors in a transportation network, with the intent to maximize the expected information gain and minimize the estimation error for the subsequent nuclear material detection stage. A Kalman filtering-based framework is adapted to assist the decision-maker in quantifying the network-wide information gain and SNM flow estimation accuracy. PMID:22163641

  18. Locating and estimating air emissions from sources of chlorobenzenes (revised March 1994). Final report

    SciTech Connect

    Not Available

    1994-03-01

    ;Table of Contents: Background; Emissions from Chlorobenzenes Production; Emissions from Major Uses of Chlorobenzene; Emission from the Use of Materials Containing Chlorobenzenes; Byproduct Emission -- Processes Unrelated to Production or Use of Chlorobenzenes; Ambient Air and Stationary Source Test Procedures; Potential Source Categories of Chlorobenzenes Emissions; Textile Fiber Dyeing Facilities with Annual Sales Greater Than $1 Million; and Summary of Emission Factors Listed in this Document.

  19. Location of odor sources and the affected population in Imperial County, California

    SciTech Connect

    Hahn, J.L.

    1981-08-01

    This report is divided into four sections. The first two sections contain general background information on Imperial County. The third section is a general discussion of odor sources in Imperial County, and the fourth maps the specific odor sources, the expected areas of perception, and the affected populations. this mapping is done for the Imperial Valley and each of the four Imperial County KGRA's (Known Geothermal Resource Areas) where odor from the development of the geothermal energy may affect population.

  20. Extraction of accurate structure-factor amplitudes from Laue data: wavelength normalization with wiggler and undulator X-ray sources.

    PubMed

    Srajer, V; Crosson, S; Schmidt, M; Key, J; Schotte, F; Anderson, S; Perman, B; Ren, Z; Teng, T Y; Bourgeois, D; Wulff, M; Moffat, K

    2000-07-01

    Wavelength normalization is an essential part of processing of Laue X-ray diffraction data and is critically important for deriving accurate structure-factor amplitudes. The results of wavelength normalization for Laue data obtained in nanosecond time-resolved experiments at the ID09 beamline at the European Synchrotron Radiation Facility, Grenoble, France, are presented. Several wiggler and undulator insertion devices with complex spectra were used. The results show that even in the most challenging cases, such as wiggler/undulator tandems or single-line undulators, accurate wavelength normalization does not require unusually redundant Laue data and can be accomplished using typical Laue data sets. Single-line undulator spectra derived from Laue data compare well with the measured incident X-ray spectra. Successful wavelength normalization of the undulator data was also confirmed by the observed signal in nanosecond time-resolved experiments. Single-line undulators, which are attractive for time-resolved experiments due to their high peak intensity and low polychromatic background, are compared with wigglers, based on data obtained on the same crystal. PMID:16609201

  1. The role of cognitive switching in head-up displays. [to determine pilot ability to accurately extract information from either of two sources

    NASA Technical Reports Server (NTRS)

    Fischer, E.

    1979-01-01

    The pilot's ability to accurately extract information from either one or both of two superimposed sources of information was determined. Static, aerial, color 35 mm slides of external runway environments and slides of corresponding static head-up display (HUD) symbology were used as the sources. A three channel tachistoscope was utilized to show either the HUD alone, the scene alone, or the two slides superimposed. Cognitive performance of the pilots was assessed by determining the percentage of correct answers given to two HUD related questions, two scene related questions, or one HUD and one scene related question.

  2. Spatial location priors for Gaussian model based reverberant audio source separation

    NASA Astrophysics Data System (ADS)

    Duong, Ngoc QK; Vincent, Emmanuel; Gribonval, Rémi

    2013-12-01

    We consider the Gaussian framework for reverberant audio source separation, where the sources are modeled in the time-frequency domain by their short-term power spectra and their spatial covariance matrices. We propose two alternative probabilistic priors over the spatial covariance matrices which are consistent with the theory of statistical room acoustics and we derive expectation-maximization algorithms for maximum a posteriori (MAP) estimation. We argue that these algorithms provide a statistically principled solution to the permutation problem and to the risk of overfitting resulting from conventional maximum likelihood (ML) estimation. We show experimentally that in a semi-informed scenario where the source positions and certain room characteristics are known, the MAP algorithms outperform their ML counterparts. This opens the way to rigorous statistical treatment of this family of models in other scenarios in the future.

  3. Effect of Anisotropic Velocity Structure on Acoustic Emission Source Location during True-Triaxial Deformation Experiments

    NASA Astrophysics Data System (ADS)

    Ghofrani Tabari, Mehdi; Goodfellow, Sebastian; Young, R. Paul

    2016-04-01

    Although true-triaxial testing (TTT) of rocks is now more extensive worldwide, stress-induced heterogeneity due to the existence of several loading boundary effects is not usually accounted for and simplified anisotropic models are used. This study focuses on the enhanced anisotropic velocity structure to improve acoustic emission (AE) analysis for an enhanced interpretation of induced fracturing. Data from a TTT on a cubic sample of Fontainebleau sandstone is used in this study to evaluate the methodology. At different stages of the experiment the True-Triaxial Geophysical Imaging Cell (TTGIC), armed with an ultrasonic and AE monitoring system, performed several velocity surveys to image velocity structure of the sample. Going beyond a hydrostatic stress state (poro-elastic phase), the rock sample went through a non-dilatational elastic phase, a dilatational non-damaging elasto-plastic phase containing initial AE activity and finally a dilatational and damaging elasto-plastic phase up to the failure point. The experiment was divided into these phases based on the information obtained from strain, velocity and AE streaming data. Analysis of the ultrasonic velocity survey data discovered that a homogeneous anisotropic core in the center of the sample is formed with ellipsoidal symmetry under the standard polyaxial setup. Location of the transducer shots were improved by implementation of different velocity models for the sample starting from isotropic and homogeneous models going toward anisotropic and heterogeneous models. The transducer shot locations showed a major improvement after the velocity model corrections had been applied especially at the final phase of the experiment. This location improvement validated our velocity model at the final phase of the experiment consisting lower-velocity zones bearing partially saturated fractures. The ellipsoidal anisotropic velocity model was also verified at the core of the cubic rock specimen by AE event location of

  4. Technique to determine location of radio sources from measurements taken on spinning spacecraft

    NASA Technical Reports Server (NTRS)

    Fainberg, J.

    1979-01-01

    The procedure developed to extract average source direction and average source size from spin-modulated radio astronomy data measured on the IMP-6 spacecraft is described. Because all measurements are used, rather than just finding maxima or minima in the data, the method is very sensitive, even in the presence of large amounts of noise. The technique is applicable to all experiments with directivity characteristics. It is suitable for onboard processing on satellites to reduce the data flow to Earth. The application to spin-modulated nonpolarized radio astronomy data is made and includes the effects of noise, background, and second source interference. The analysis was tested with computer simulated data and the results agree with analytic predictions. Applications of this method with IMP-6 radio data have led to: (1) determination of source positions of traveling solar radio bursts at large distances from the Sun; (2) mapping of magnetospheric radio emissions by radio triangulation; and (3) detection of low frequency radio emissions from Jupiter and Saturn.

  5. Identifying constituent spectra sources in multispectral images to quantify and locate cervical neoplasia

    NASA Astrophysics Data System (ADS)

    Baker, Kevin C.; Bambot, Shabbir

    2011-02-01

    Optical spectroscopy has been shown to be an effective method for detecting neoplasia. Guided Therapeutics has developed LightTouch, a non invasive device that uses a combination of reflectance and fluorescence spectroscopy for identifying early cancer of the human cervix. The combination of the multispectral information from the two spectroscopic modalities has been shown to be an effective method to screen for cervical cancer. There has however been a relative paucity of work in identifying the individual spectral components that contribute to the measured fluorescence and reflectance spectra. This work aims to identify the constituent source spectra and their concentrations. We used non-negative matrix factorization (NNMF) numerical methods to decompose the mixed multispectral data into the constituent spectra and their corresponding concentrations. NNMF is an iterative approach that factorizes the measured data into non-negative factors. The factors are chosen to minimize the root-mean-squared residual error. NNMF has shown promise for feature extraction and identification in the fields of text mining and spectral data analysis. Since both the constituent source spectra and their corresponding concentrations are assumed to be non-negative by nature NNMF is a reasonable approach to deconvolve the measured multispectral data. Supervised learning methods were then used to determine which of the constituent spectra sources best predict the amount of neoplasia. The constituent spectra sources found to best predict neoplasia were then compared with spectra of known biological chromophores.

  6. Subjective Preference for Sound Sources Located on the Stage and in the Orchestra Pit of AN Opera House

    NASA Astrophysics Data System (ADS)

    Sato, S.; Sakai, H.; Prodi, N.

    2002-11-01

    The present study investigates whether the subjective preference theory can be applied to the sound field in an opera house. Paired-comparison tests were conducted to obtain scale values of subjective preference. As the source locations of the music on the stage and in the orchestra pit were moved, listeners were asked to give their acoustical preference. The acoustical factors at each listening position were obtained from the interaural cross-correlation function and binaural impulse responses measured at each listening position. The relationship between the scale values of subjective preference and orthogonal acoustical factors ( LL, IACC, τIACC, Δt 1 for the pit source, Δt 1 for the stage, T sub for the pit source, and T sub for the stage source) was determined by using factor analysis, which shows that the preference theory is applicable. Total scores obtained from factor analysis and measured scale values are in good agreement.

  7. Fuel from wastewater : harnessing a potential energy source in Canada through the co-location of algae biofuel production to sources of effluent, heat and CO2.

    SciTech Connect

    Passell, Howard David; Whalen, Jake; Pienkos, Philip P.; O'Leary, Stephen J.; Roach, Jesse Dillon; Moreland, Barbara D.; Klise, Geoffrey Taylor

    2010-12-01

    Sandia National Laboratories is collaborating with the National Research Council (NRC) Canada and the National Renewable Energy Laboratory (NREL) to develop a decision-support model that will evaluate the tradeoffs associated with high-latitude algae biofuel production co-located with wastewater, CO2, and waste heat. This project helps Canada meet its goal of diversifying fuel sources with algae-based biofuels. The biofuel production will provide a wide range of benefits including wastewater treatment, CO2 reuse and reduction of demand for fossil-based fuels. The higher energy density in algae-based fuels gives them an advantage over crop-based biofuels as the 'production' footprint required is much less, resulting in less water consumed and little, if any conversion of agricultural land from food to fuel production. Besides being a potential source for liquid fuel, algae have the potential to be used to generate electricity through the burning of dried biomass, or anaerobically digested to generate methane for electricity production. Co-locating algae production with waste streams may be crucial for making algae an economically valuable fuel source, and will certainly improve its overall ecological sustainability. The modeling process will address these questions, and others that are important to the use of water for energy production: What are the locations where all resources are co-located, and what volumes of algal biomass and oil can be produced there? In locations where co-location does not occur, what resources should be transported, and how far, while maintaining economic viability? This work is being funded through the U.S. Department of Energy (DOE) Biomass Program Office of Energy Efficiency and Renewable Energy, and is part of a larger collaborative effort that includes sampling, strain isolation, strain characterization and cultivation being performed by the NREL and Canada's NRC. Results from the NREL / NRC collaboration including specific

  8. Can Handheld Plastic Detectors Do Both Gamma and Neutron Isotopic Identification with Directional Source Location?

    SciTech Connect

    Robert Hayes

    2008-04-18

    This paper demonstrates, through MCNPX simulations, that a compact hexagonal array of detectors can be utilized to do both gamma isotopic identification (ID) along with neutron identification while simultaneously finding the direction of the source relative to the detector array. The detector array itself is composed of seven borated polyvinyl toluene (PVT) hexagonal light pipes approximately 4 inches long and with a 1.25 inch face-to-face thickness assembled in a tight configuration. The gamma ID capability is realized through judicious windowing algorithms as is the neutron spectral unfolding. By having multiple detectors in different relative positions, directional determination of the source can be realized. By further adding multiplicity counters to the neutron counts, fission events can be measured.

  9. Acoustic source location in a jet-blown flap using a cross-correlation technique

    NASA Technical Reports Server (NTRS)

    Becker, R. S.; Maus, J. R.

    1977-01-01

    The acoustic source strength distribution in a turbulent flow field was measured for two far field microphones at 45 deg above and below the plane of the flap surface. A processed signal from an inclined hot-film anemometry probe was cross correlated with the signal from the appropriate far field microphone. The contribution made by the sources associated with the fluctuating pressure on the flap surface to the sound received at far field microphone was estimated by cross correlating the processed signals of microphones which were embedded in the flap surface with the far field microphone signals. In addition, detailed fluid dynamic measurements were made in the flow field of the jet flap using dual sensor hot-film anemometry probes.

  10. Locating very high energy gamma-ray sources with arcminute accuracy

    NASA Technical Reports Server (NTRS)

    Akerlof, C. W.; Cawley, M. F.; Chantell, M.; Harris, K.; Lawrence, M. A.; Fegan, D. J.; Lang, M. J.; Hillas, A. M.; Jennings, D. G.; Lamb, R. C.

    1991-01-01

    The angular accuracy of gamma-ray detectors is intrinsically limited by the physical processes involved in photon detection. Although a number of pointlike sources were detected by the COS B satellite, only two have been unambiguously identified by time signature with counterparts at longer wavelengths. By taking advantage of the extended longitudinal structure of VHE gamma-ray showers, measurements in the TeV energy range can pinpoint source coordinates to arcminute accuracy. This has now been demonstrated with new data analysis procedures applied to observations of the Crab Nebula using Cherenkov air shower imaging techniques. With two telescopes in coincidence, the individual event circular probable error will be 0.13 deg. The half-cone angle of the field of view is effectively 1 deg.

  11. Locating very high energy gamma ray sources with arc minute accuracy

    NASA Technical Reports Server (NTRS)

    Akerlof, C. W.; Cawley, M. F.; Chantell, M.; Fegan, D. J.; Harris, K.; Hillas, A. M.; Jennings, D. G.; Lamb, R. C.; Lawrence, M. A.; Lang, M. J.

    1992-01-01

    The angular accuracy of gamma-ray detectors is intrinsically limited by the physical processes involved in photon detection. Although a number of point-like sources were detected by the COS-B satellite, only two were unambiguously identified by time signature with counterparts at longer wavelengths. By taking advantage of the extended longitudinal structure of Very High Energy gamma-ray showers, measurements in the TeV energy range can pinpoint source coordinates to arc minute accuracy. This was demonstrated using Cerenkov air shower imaging techniques. With two telescopes in coincidence, the individual event circular probable error will be 0.13 deg. The half-cone angle of the field of view is effectively 1 deg.

  12. Revision of earthquake hypocenter locations in GEOFON bulletin data using global source-specific station terms technique

    NASA Astrophysics Data System (ADS)

    Nooshiri, N.; Saul, J.; Heimann, S.; Tilmann, F. J.; Dahm, T.

    2015-12-01

    The use of a 1D velocity model for seismic event location is often associated with significant travel-time residuals. Particularly for regional stations in subduction zones, where the velocity structure strongly deviates from the assumed 1D model, residuals of up to ±10 seconds are observed even for clear arrivals, which leads to strongly biased locations. In fact, due to mostly regional travel-time anomalies, arrival times at regional stations do not match the location obtained with teleseismic picks, and vice versa. If the earthquake is weak and only recorded regionally, or if fast locations based on regional stations are needed, the location may be far off the corresponding teleseismic location. In this case, implementation of travel-time corrections may leads to a reduction of the travel-time residuals at regional stations and, in consequence, significantly improve the relative location accuracy. Here, we have extended the source-specific station terms (SSST) technique to regional and teleseismic distances and adopted the algorithm for probabilistic, non-linear, global-search earthquake location. The method has been applied to specific test regions using P and pP phases from the GEOFON bulletin data for all available station networks. By using this method, a set of timing corrections has been calculated for each station varying as a function of source position. In this way, an attempt is made to correct for the systematic errors, introduced by limitations and inaccuracies in the assumed velocity structure, without solving for a new earth model itself. In this presentation, we draw on examples of the application of this global SSST technique to relocate earthquakes from the Tonga-Fiji subduction zone and from the Chilean margin. Our results have been showing a considerable decrease of the root-mean-square (RMS) residual in earthquake location final catalogs, a major reduction of the median absolute deviation (MAD) of the travel

  13. Source Apportionment of Particle Bound Polycyclic Aromatic Hydrocarbons at an Industrial Location in Agra, India

    PubMed Central

    Lakhani, Anita

    2012-01-01

    16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) were quantified in total suspended ambient particulate matter (TSPM) collected from an industrial site in Agra (India) using gas chromatography. The major industrial activities in Agra are foundries that previously used coal and coke as fuel in cupola furnaces. These foundries have now switched over to natural gas. In addition, use of compressed natural gas has also been promoted and encouraged in automobiles. This study attempts to apportion sources of PAH in the ambient air and the results reflect the advantages associated with the change of fuel. The predominant PAHs in TSPM include high molecular weight (HMW) congeners BghiP, DbA, IP, and BaP. The sum of 16 priority PAHs had a mean value of 72.7 ± 4.7 ng m−3. Potential sources of PAHs in aerosols were identified using diagnostic ratios and principal component analysis. The results reflect a blend of emissions from diesel and natural gas as the major sources of PAH in the city along with contribution from emission of coal, coke, and gasoline. PMID:22606062

  14. Long-term particle measurements in Finnish Arctic: Part II - Trend analysis and source location identification

    NASA Astrophysics Data System (ADS)

    Laing, James R.; Hopke, Philip K.; Hopke, Eleanor F.; Husain, Liaquat; Dutkiewicz, Vincent A.; Paatero, Jussi; Viisanen, Yrjö.

    2014-05-01

    Forty-seven years (1964-2010) of weekly trace metal and major ion concentrations in total suspended particle samples from Kevo, Finland were analyzed for long-term trends and by source identification methods. Significant long-term decreasing trends were detected for most species. The largest decreases over the 47 years were Sb (-3.90% yr-1), Pb (-3.87% yr-1), Mn (-3.45% yr-1), Cd (-3.42% yr-1), and Ca (-3.13% yr-1). As, Pb, and Cd concentrations at Kevo were consistent with the reported time-trends of European emissions inventories. Pb concentrations at Kevo have dramatically decreased (92%) in the past 47 years due to the reduced use of leaded gasoline in automobiles. Back-trajectory analysis suggests that the main source areas of anthropogenic species (V, Cd, Mn, Mo, Sb, Tl, W) were predominantly in Eastern Europe, European Russia, and the Baltics. Markers of stationary fuel combustion (V, Mn, Mo, Sb, Se, and Tl) pointed towards source regions in the Pechora Basin and Ural industrial areas in Russia, and near gas and oil fields in western Kazakhstan.

  15. Source apportionment of particle bound polycyclic aromatic hydrocarbons at an industrial location in Agra, India.

    PubMed

    Lakhani, Anita

    2012-01-01

    16 U.S. EPA priority polycyclic aromatic hydrocarbons (PAHs) were quantified in total suspended ambient particulate matter (TSPM) collected from an industrial site in Agra (India) using gas chromatography. The major industrial activities in Agra are foundries that previously used coal and coke as fuel in cupola furnaces. These foundries have now switched over to natural gas. In addition, use of compressed natural gas has also been promoted and encouraged in automobiles. This study attempts to apportion sources of PAH in the ambient air and the results reflect the advantages associated with the change of fuel. The predominant PAHs in TSPM include high molecular weight (HMW) congeners BghiP, DbA, IP, and BaP. The sum of 16 priority PAHs had a mean value of 72.7 ± 4.7 ng m(-3). Potential sources of PAHs in aerosols were identified using diagnostic ratios and principal component analysis. The results reflect a blend of emissions from diesel and natural gas as the major sources of PAH in the city along with contribution from emission of coal, coke, and gasoline. PMID:22606062

  16. Argon Cluster Sputtering Source for ToF-SIMS Depth Profiling of Insulating Materials: High Sputter Rate and Accurate Interfacial Information.

    PubMed

    Wang, Zhaoying; Liu, Bingwen; Zhao, Evan W; Jin, Ke; Du, Yingge; Neeway, James J; Ryan, Joseph V; Hu, Dehong; Zhang, Kelvin H L; Hong, Mina; Le Guernic, Solenne; Thevuthasan, Suntharampilai; Wang, Fuyi; Zhu, Zihua

    2015-08-01

    The use of an argon cluster ion sputtering source has been demonstrated to perform superiorly relative to traditional oxygen and cesium ion sputtering sources for ToF-SIMS depth profiling of insulating materials. The superior performance has been attributed to effective alleviation of surface charging. A simulated nuclear waste glass (SON68) and layered hole-perovskite oxide thin films were selected as model systems because of their fundamental and practical significance. Our results show that high sputter rates and accurate interfacial information can be achieved simultaneously for argon cluster sputtering, whereas this is not the case for cesium and oxygen sputtering. Therefore, the implementation of an argon cluster sputtering source can significantly improve the analysis efficiency of insulating materials and, thus, can expand its applications to the study of glass corrosion, perovskite oxide thin film characterization, and many other systems of interest. PMID:25953490

  17. Argon Cluster Sputtering Source for ToF-SIMS Depth Profiling of Insulating Materials: High Sputter Rate and Accurate Interfacial Information

    NASA Astrophysics Data System (ADS)

    Wang, Zhaoying; Liu, Bingwen; Zhao, Evan W.; Jin, Ke; Du, Yingge; Neeway, James J.; Ryan, Joseph V.; Hu, Dehong; Zhang, Kelvin H. L.; Hong, Mina; Le Guernic, Solenne; Thevuthasan, Suntharampilai; Wang, Fuyi; Zhu, Zihua

    2015-08-01

    The use of an argon cluster ion sputtering source has been demonstrated to perform superiorly relative to traditional oxygen and cesium ion sputtering sources for ToF-SIMS depth profiling of insulating materials. The superior performance has been attributed to effective alleviation of surface charging. A simulated nuclear waste glass (SON68) and layered hole-perovskite oxide thin films were selected as model systems because of their fundamental and practical significance. Our results show that high sputter rates and accurate interfacial information can be achieved simultaneously for argon cluster sputtering, whereas this is not the case for cesium and oxygen sputtering. Therefore, the implementation of an argon cluster sputtering source can significantly improve the analysis efficiency of insulating materials and, thus, can expand its applications to the study of glass corrosion, perovskite oxide thin film characterization, and many other systems of interest.

  18. Locating single-point sources from arrival times containing large picking errors (LPEs): the virtual field optimization method (VFOM)

    NASA Astrophysics Data System (ADS)

    Li, Xi-Bing; Wang, Ze-Wei; Dong, Long-Jun

    2016-01-01

    Microseismic monitoring systems using local location techniques tend to be timely, automatic and stable. One basic requirement of these systems is the automatic picking of arrival times. However, arrival times generated by automated techniques always contain large picking errors (LPEs), which may make the location solution unreliable and cause the integrated system to be unstable. To overcome the LPE issue, we propose the virtual field optimization method (VFOM) for locating single-point sources. In contrast to existing approaches, the VFOM optimizes a continuous and virtually established objective function to search the space for the common intersection of the hyperboloids, which is determined by sensor pairs other than the least residual between the model-calculated and measured arrivals. The results of numerical examples and in-site blasts show that the VFOM can obtain more precise and stable solutions than traditional methods when the input data contain LPEs. Furthermore, we discuss the impact of LPEs on objective functions to determine the LPE-tolerant mechanism, velocity sensitivity and stopping criteria of the VFOM. The proposed method is also capable of locating acoustic sources using passive techniques such as passive sonar detection and acoustic emission.

  19. Locating single-point sources from arrival times containing large picking errors (LPEs): the virtual field optimization method (VFOM).

    PubMed

    Li, Xi-Bing; Wang, Ze-Wei; Dong, Long-Jun

    2016-01-01

    Microseismic monitoring systems using local location techniques tend to be timely, automatic and stable. One basic requirement of these systems is the automatic picking of arrival times. However, arrival times generated by automated techniques always contain large picking errors (LPEs), which may make the location solution unreliable and cause the integrated system to be unstable. To overcome the LPE issue, we propose the virtual field optimization method (VFOM) for locating single-point sources. In contrast to existing approaches, the VFOM optimizes a continuous and virtually established objective function to search the space for the common intersection of the hyperboloids, which is determined by sensor pairs other than the least residual between the model-calculated and measured arrivals. The results of numerical examples and in-site blasts show that the VFOM can obtain more precise and stable solutions than traditional methods when the input data contain LPEs. Furthermore, we discuss the impact of LPEs on objective functions to determine the LPE-tolerant mechanism, velocity sensitivity and stopping criteria of the VFOM. The proposed method is also capable of locating acoustic sources using passive techniques such as passive sonar detection and acoustic emission. PMID:26754955

  20. Locating single-point sources from arrival times containing large picking errors (LPEs): the virtual field optimization method (VFOM)

    PubMed Central

    Li, Xi-Bing; Wang, Ze-Wei; Dong, Long-Jun

    2016-01-01

    Microseismic monitoring systems using local location techniques tend to be timely, automatic and stable. One basic requirement of these systems is the automatic picking of arrival times. However, arrival times generated by automated techniques always contain large picking errors (LPEs), which may make the location solution unreliable and cause the integrated system to be unstable. To overcome the LPE issue, we propose the virtual field optimization method (VFOM) for locating single-point sources. In contrast to existing approaches, the VFOM optimizes a continuous and virtually established objective function to search the space for the common intersection of the hyperboloids, which is determined by sensor pairs other than the least residual between the model-calculated and measured arrivals. The results of numerical examples and in-site blasts show that the VFOM can obtain more precise and stable solutions than traditional methods when the input data contain LPEs. Furthermore, we discuss the impact of LPEs on objective functions to determine the LPE-tolerant mechanism, velocity sensitivity and stopping criteria of the VFOM. The proposed method is also capable of locating acoustic sources using passive techniques such as passive sonar detection and acoustic emission. PMID:26754955

  1. Arcsec source location measurements in gamma-ray astronomy from a lunar observatory

    NASA Technical Reports Server (NTRS)

    Koch, David G.; Hughes, E. B.

    1990-01-01

    The physical processes typically used in the detection of high energy gamma-rays do not permit good angular resolution, which makes difficult the unambiguous association of discrete gamma-ray sources with objects emitting at other wavelengths. This problem can be overcome by placing gamma-ray detectors on the moon and using the horizon as an occulting edge to achieve arcsec resolution. For the purpose of discussion, this concept is examined for gamma rays above about 20 MeV for which pair production dominates the detection process and locally-generated nuclear gamma rays do not contribute to the background.

  2. On the preferred source location for the convective amplification of ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Horne, Richard B.; Thorne, Richard M.

    1993-01-01

    The propagation, growth, and absorption of electromagnetic ion cyclotron waves (EMICs) in the Pc1 range are studied using the HOTRAY ray tracing program for a realistic distribution of thermal plasma (H+, He+, O+), which is assumed to be in diffusive equilibrium inside the plasmasphere and collisionless in the low-density region outside the plasmapause. It is demonstrated that there are two principal source regions for the growth of EMIC waves. The theoretical results are related to the most recent satellite and ground-based observations.

  3. XMM-NEWTON OBSERVATIONS OF FIVE INTEGRAL SOURCES LOCATED TOWARD THE SCUTUM ARM

    SciTech Connect

    Bodaghee, A.; Tomsick, J. A.; Rodriguez, J.

    2012-07-01

    Results are presented for XMM-Newton observations of five hard X-ray sources discovered by INTEGRAL in the direction of the Scutum Arm. Each source received {approx}>20 ks of effective exposure time. We provide refined X-ray positions for all five targets enabling us to pinpoint the most likely counterpart in optical/infrared archives. Spectral and timing information (much of which is provided for the first time) allow us to give a firm classification for IGR J18462-0223 and to offer tentative classifications for the others. For IGR J18462-0223, we discovered a coherent pulsation period of 997 {+-} 1 s, which we attribute to the spin of a neutron star in a highly obscured (N{sub H} =2 Multiplication-Sign 10{sup 23} cm{sup -2}) high-mass X-ray binary (HMXB). This makes IGR J18462-0223 the seventh supergiant fast X-ray transient candidate with a confirmed pulsation period. IGR J18457+0244 is a highly absorbed (N{sub H} =8 Multiplication-Sign 10{sup 23} cm{sup -2}) source in which the possible detection of an iron line suggests an active galactic nucleus (AGN) of type Sey-2 situated at z = 0.07(1). A periodic signal at 4.4 ks could be a quasi-periodic oscillation which would make IGR J18457+0244 one of a handful of AGNs in which such features have been claimed, but a slowly rotating neutron star in an HMXB cannot be ruled out. IGR J18482+0049 represents a new obscured HMXB candidate with N{sub H} =4 Multiplication-Sign 10{sup 23} cm{sup -2}. We tentatively propose that IGR J18532+0416 is either an AGN or a pulsar in an HMXB system. The X-ray spectral properties of IGR J18538-0102 are consistent with the AGN classification that has been proposed for this source.

  4. Gamma-ray burst locations from the Burst and Transient Source Experiment

    NASA Technical Reports Server (NTRS)

    Brock, M. N.; Meegan, C. A.; Roberts, F. E.; Fishman, G. J.; Wilson, R. B.; Paciesas, W. S.; Pendleton, G. N.

    1992-01-01

    The Burst and Transient Source Experiment (BATSE) consists of eight anisotropic gamma-ray spectrometers at the corners of the Compton Gamma Ray Observatory. BATSE monitors the full sky from a fixed orientation and determines the direction of gamma-ray bursts with an accuracy appropriate for studying the bursts' celestial distribution. We describe the calculation of gamma-ray burst directions from measurements made by BATSE. We present a sample of calculated directions from BATSE's measurement of solar flaxes and compare the calculated directions with the solar direction. We describe the systematic errors apparent in these data and discuss ongoing efforts to correct them.

  5. Metamaterials-based sensor to detect and locate nonlinear elastic sources

    NASA Astrophysics Data System (ADS)

    Gliozzi, Antonio S.; Miniaci, Marco; Bosia, Federico; Pugno, Nicola M.; Scalerandi, Marco

    2015-10-01

    In recent years, acoustic metamaterials have attracted increasing scientific interest for very diverse technological applications ranging from sound abatement to ultrasonic imaging, mainly due to their ability to act as band-stop filters. At the same time, the concept of chaotic cavities has been recently proposed as an efficient tool to enhance the quality of nonlinear signal analysis, particularly in the ultrasonic/acoustic case. The goal of the present paper is to merge the two concepts in order to propose a metamaterial-based device that can be used as a natural and selective linear filter for the detection of signals resulting from the propagation of elastic waves in nonlinear materials, e.g., in the presence of damage, and as a detector for the damage itself in time reversal experiments. Numerical simulations demonstrate the feasibility of the approach and the potential of the device in providing improved signal-to-noise ratios and enhanced focusing on the defect locations.

  6. Metamaterials-based sensor to detect and locate nonlinear elastic sources

    SciTech Connect

    Gliozzi, Antonio S.; Scalerandi, Marco; Miniaci, Marco; Bosia, Federico; Pugno, Nicola M.

    2015-10-19

    In recent years, acoustic metamaterials have attracted increasing scientific interest for very diverse technological applications ranging from sound abatement to ultrasonic imaging, mainly due to their ability to act as band-stop filters. At the same time, the concept of chaotic cavities has been recently proposed as an efficient tool to enhance the quality of nonlinear signal analysis, particularly in the ultrasonic/acoustic case. The goal of the present paper is to merge the two concepts in order to propose a metamaterial-based device that can be used as a natural and selective linear filter for the detection of signals resulting from the propagation of elastic waves in nonlinear materials, e.g., in the presence of damage, and as a detector for the damage itself in time reversal experiments. Numerical simulations demonstrate the feasibility of the approach and the potential of the device in providing improved signal-to-noise ratios and enhanced focusing on the defect locations.

  7. Sound frequency-invariant neural coding of a frequency-dependent cue to sound source location.

    PubMed

    Jones, Heath G; Brown, Andrew D; Koka, Kanthaiah; Thornton, Jennifer L; Tollin, Daniel J

    2015-07-01

    The century-old duplex theory of sound localization posits that low- and high-frequency sounds are localized with two different acoustical cues, interaural time and level differences (ITDs and ILDs), respectively. While behavioral studies in humans and behavioral and neurophysiological studies in a variety of animal models have largely supported the duplex theory, behavioral sensitivity to ILD is curiously invariant across the audible spectrum. Here we demonstrate that auditory midbrain neurons in the chinchilla (Chinchilla lanigera) also encode ILDs in a frequency-invariant manner, efficiently representing the full range of acoustical ILDs experienced as a joint function of sound source frequency, azimuth, and distance. We further show, using Fisher information, that nominal "low-frequency" and "high-frequency" ILD-sensitive neural populations can discriminate ILD with similar acuity, yielding neural ILD discrimination thresholds for near-midline sources comparable to behavioral discrimination thresholds estimated for chinchillas. These findings thus suggest a revision to the duplex theory and reinforce ecological and efficiency principles that hold that neural systems have evolved to encode the spectrum of biologically relevant sensory signals to which they are naturally exposed. PMID:25972580

  8. On the location of microseismic sources in instable rock slope areas: heterogeneous vs. homogenous 3D velocity models

    NASA Astrophysics Data System (ADS)

    Coviello, Velio; Manconi, Andrea; Occhiena, Cristina; Arattano, Massimo; Scavia, Claudio

    2013-04-01

    Rock-falls are one of the most common and hazardous phenomena occurring in mountainous areas. The formation of cracks in rocks is often accompanied by a sudden release of energy, which propagates in form of elastic waves and can be detected by a suitable transducer array. Therefore, geophones are among the most effective monitoring devices to investigate eventual precursors of rock-fall phenomena. However, the identification of an efficient procedure to forecast rock-fall occurrence in space and time is still an open challenge. In this study, we aim at developing an efficient procedure to locate microseismic sources relevant to cracking mechanisms, and thus gather indications on eventual precursors of rock-fall phenomena. Common seismic location tools usually implement homogeneous or multilayered velocity models but, in case of high slope gradients and heavily fractured rock masses, these simplifications may lead to errors on the correct estimation of the source location. Thus, we analyzed how the consideration of 3D material properties on the propagation medium may influence the location. In the framework of the Alcotra 2007-2013 Project MASSA (Medium And Small Size rock-fall hazard Assessment), a monitoring system composed by 8 triaxial geophones was installed in 2010 at the J.A. Carrel hut (3829 m a.s.l., Matterhorn, NW Italian Alps) and during the first year of operation the network recorded more than 600 natural events that exceeded a fixed threshold [1]. Despite the harsh environmental conditions of the study area, eighteen points distributed as uniformly as possible in space were selected for hammering. The artificial source dataset of known coordinates was used to constrain a 3D heterogeneous velocity model through a Simultaneous Iterative Reconstructive Technique. In order to mitigate the intrinsic uncertainties of the inversion procedure, bootstrapping was performed to extend the dataset and a statistical analysis was issued to improve the model

  9. Accurate positions for the ultraluminous X-ray sources NGC 7319-X4 and NGC 5474-X1 and limiting magnitudes for their optical counterparts

    NASA Astrophysics Data System (ADS)

    Heida, M.; Jonker, P. G.; Torres, M. A. P.; Mineo, S.

    2012-08-01

    In this paper, we report accurate Chandra positions for two ultraluminous X-ray sources (ULXs): NGC 7319-X4 at Right Ascension (RA) = 339?029 17(2), Declination (Dec.) = 33?974 76(2) and NGC 5474-X1 at RA = 211?248 59(3), Dec. = 53?635 84(3). We perform bore-sight corrections on the Chandra X-ray satellite observations of these sources to get these accurate positions of the X-ray sources and match these positions with archival optical data from the Wide Field Planetary Camera 2 (WFPC2) onboard the Hubble Space Telescope. We do not find the optical counterparts; the limiting absolute magnitudes of the observations in the WFPC2 standard magnitude system are B=-7.9, V=-8.7 and I=-9.3 for NGC 7319-X4 and U=-6.4 for NGC 5474-X1. We report on the X-ray spectral properties and find evidence for X-ray variability in NGC 5474-X1. Finally, we briefly discuss several options for the nature of these ULXs.

  10. Determining the seismic source mechanism and location for an explosive eruption with limited observational data: Augustine Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Dawson, Phillip B.; Chouet, Bernard A.; Power, John

    2011-02-01

    Waveform inversions of the very-long-period components of the seismic wavefield produced by an explosive eruption that occurred on 11 January, 2006 at Augustine Volcano, Alaska constrain the seismic source location to near sea level beneath the summit of the volcano. The calculated moment tensors indicate the presence of a volumetric source mechanism. Systematic reconstruction of the source mechanism shows the source consists of a sill intersected by either a sub-vertical east-west trending dike or a sub-vertical pipe and a weak single force. The trend of the dike may be controlled by the east-west trending Augustine-Seldovia arch. The data from the network of broadband sensors is limited to fourteen seismic traces, and synthetic modeling confirms the ability of the network to recover the source mechanism. The synthetic modeling also provides a guide to the expected capability of a broadband network to resolve very-long-period source mechanisms, particularly when confronted with limited observational data.

  11. Determining the seismic source mechanism and location for an explosive eruption with limited observational data: Augustine Volcano, Alaska

    USGS Publications Warehouse

    Dawson, P.B.; Chouet, B.A.; Power, J.

    2011-01-01

    Waveform inversions of the very-long-period components of the seismic wavefield produced by an explosive eruption that occurred on 11 January, 2006 at Augustine Volcano, Alaska constrain the seismic source location to near sea level beneath the summit of the volcano. The calculated moment tensors indicate the presence of a volumetric source mechanism. Systematic reconstruction of the source mechanism shows the source consists of a sill intersected by either a sub-vertical east-west trending dike or a sub-vertical pipe and a weak single force. The trend of the dike may be controlled by the east-west trending Augustine-Seldovia arch. The data from the network of broadband sensors is limited to fourteen seismic traces, and synthetic modeling confirms the ability of the network to recover the source mechanism. The synthetic modeling also provides a guide to the expected capability of a broadband network to resolve very-long-period source mechanisms, particularly when confronted with limited observational data. Copyright 2011 by the American Geophysical Union.

  12. Site Characterization of the Source Physics Experiment Phase II Location Using Seismic Reflection Data

    SciTech Connect

    Sexton, Emily; Snelson, Catherine M; Chipman, Veraun D; Emer, Dudley; White, Bob; Emmit, Ryan; Wright, Al; Drellack, Sigmund; Huckins-Gang, Heather; Mercadante, Jennifer; Floyd, Michael; McGowin, Chris; Cothrun, Chris; Bonal, Nedra

    2013-12-05

    An objective of the Source Physics Experiment (SPE) is to identify low-yield nuclear explosions from a regional distance. Low-yield nuclear explosions can often be difficult to discriminate among the clutter of natural and man-made explosive events (e.g., earthquakes and mine blasts). The SPE is broken into three phases. Phase I has provided the first of the physics-based data to test the empirical models that have been used to discriminate nuclear events. The Phase I series of tests were placed within a highly fractured granite body. The evolution of the project has led to development of Phase II, to be placed within the opposite end member of geology, an alluvium environment, thereby increasing the database of waveforms to build upon in the discrimination models. Both the granite and alluvium sites have hosted nearby nuclear tests, which provide comparisons for the chemical test data. Phase III of the SPE is yet to be determined.

  13. Underwater Measurement of the Sound-Intensity Vector: its Use in Locating Sound Sources, and in Measuring the Sound Power of Stationary and Living Sources

    NASA Astrophysics Data System (ADS)

    Wei, Wei

    Instrumentation was developed to measure the components of the sound-intensity vector (i.e. sound-power flow per unit area) in water using the cross-spectral method. This consists of a probe with four closely-spaced hydrophones in a tetrahedral arrangement, and associated equipment including three two-channel FFT analyzers. The hydrophones are closely spaced (i.e. less than a tenth of a wavelength apart) to permit accurate measurement of the intensity vector at a point in space, over a reasonable frequency range. For the probe used in the dissertation research, the frequency range extends up to about 13 kHz. The accuracy of the prototype probe in measuring the direction of a sound source without noise interference, is shown to be within +/-2 degrees. Tests were conducted in a water tank to test the accuracy of direction finding with different types of acoustic interference: (a) boundary reverberation, (b) ambient background noise and (c) another sound source. It is shown that a source can be detected with good accuracy when the pressure level signal-to-noise ratio is -2dB. Several techniques can be used to separate the directions of multiple sound sources, i.e. (a) spectral weighting, (b) spectral subtraction and (c) solving systems of nonlinear equations based on vector intensity and pressure measurements. The first two are demonstrated in the dissertation. The direction-finding ability of the vector probe was used to determine the sound power of a moving source, the probe being used to track the source and simultaneously to measure its sound intensity. The sound power of the moving source is compared to the sound power of the source: (a) estimated from the measured voltage applied to the hydrophone and the typical transmitting response curve supplied by the hydrophone manufacturer, and (b) measured when the source is stationary. In the first comparison, the sound power of the moving source is about 14% or 0.5dB larger and in the second it is about 18% or 0.7d

  14. Seismic swarm associated with the 2008 eruption of Kasatochi Volcano, Alaska: earthquake locations and source parameters

    USGS Publications Warehouse

    Ruppert, Natalia G.; Prejean, Stephanie G.; Hansen, Roger A.

    2011-01-01

    An energetic seismic swarm accompanied an eruption of Kasatochi Volcano in the central Aleutian volcanic arc in August of 2008. In retrospect, the first earthquakes in the swarm were detected about 1 month prior to the eruption onset. Activity in the swarm quickly intensified less than 48 h prior to the first large explosion and subsequently subsided with decline of eruptive activity. The largest earthquake measured as moment magnitude 5.8, and a dozen additional earthquakes were larger than magnitude 4. The swarm exhibited both tectonic and volcanic characteristics. Its shear failure earthquake features were b value = 0.9, most earthquakes with impulsive P and S arrivals and higher-frequency content, and earthquake faulting parameters consistent with regional tectonic stresses. Its volcanic or fluid-influenced seismicity features were volcanic tremor, large CLVD components in moment tensor solutions, and increasing magnitudes with time. Earthquake location tests suggest that the earthquakes occurred in a distributed volume elongated in the NS direction either directly under the volcano or within 5-10 km south of it. Following the MW 5.8 event, earthquakes occurred in a new crustal volume slightly east and north of the previous earthquakes. The central Aleutian Arc is a tectonically active region with seismicity occurring in the crusts of the Pacific and North American plates in addition to interplate events. We postulate that the Kasatochi seismic swarm was a manifestation of the complex interaction of tectonic and magmatic processes in the Earth's crust. Although magmatic intrusion triggered the earthquakes in the swarm, the earthquakes failed in context of the regional stress field.

  15. Seismic swarm associated with the 2008 eruption of Kasatochi Volcano, Alaska: Earthquake locations and source parameters

    USGS Publications Warehouse

    Ruppert, N.A.; Prejean, S.; Hansen, R.A.

    2011-01-01

    An energetic seismic swarm accompanied an eruption of Kasatochi Volcano in the central Aleutian volcanic arc in August of 2008. In retrospect, the first earthquakes in the swarm were detected about 1 month prior to the eruption onset. Activity in the swarm quickly intensified less than 48 h prior to the first large explosion and subsequently subsided with decline of eruptive activity. The largest earthquake measured as moment magnitude 5.8, and a dozen additional earthquakes were larger than magnitude 4. The swarm exhibited both tectonic and volcanic characteristics. Its shear failure earthquake features were b value = 0.9, most earthquakes with impulsive P and S arrivals and higher-frequency content, and earthquake faulting parameters consistent with regional tectonic stresses. Its volcanic or fluid-influenced seismicity features were volcanic tremor, large CLVD components in moment tensor solutions, and increasing magnitudes with time. Earthquake location tests suggest that the earthquakes occurred in a distributed volume elongated in the NS direction either directly under the volcano or within 5-10 km south of it. Following the MW 5.8 event, earthquakes occurred in a new crustal volume slightly east and north of the previous earthquakes. The central Aleutian Arc is a tectonically active region with seismicity occurring in the crusts of the Pacific and North American plates in addition to interplate events. We postulate that the Kasatochi seismic swarm was a manifestation of the complex interaction of tectonic and magmatic processes in the Earth's crust. Although magmatic intrusion triggered the earthquakes in the swarm, the earthquakes failed in context of the regional stress field. Copyright ?? 2011 by the American Geophysical Union.

  16. Characterizing and locating air pollution sources in a complex industrial district using optical remote sensing technology and multivariate statistical modeling.

    PubMed

    Chang, Pao-Erh Paul; Yang, Jen-Chih Rena; Den, Walter; Wu, Chang-Fu

    2014-09-01

    Emissions of volatile organic compounds (VOCs) are most frequent environmental nuisance complaints in urban areas, especially where industrial districts are nearby. Unfortunately, identifying the responsible emission sources of VOCs is essentially a difficult task. In this study, we proposed a dynamic approach to gradually confine the location of potential VOC emission sources in an industrial complex, by combining multi-path open-path Fourier transform infrared spectrometry (OP-FTIR) measurement and the statistical method of principal component analysis (PCA). Close-cell FTIR was further used to verify the VOC emission source by measuring emitted VOCs from selected exhaust stacks at factories in the confined areas. Multiple open-path monitoring lines were deployed during a 3-month monitoring campaign in a complex industrial district. The emission patterns were identified and locations of emissions were confined by the wind data collected simultaneously. N,N-Dimethyl formamide (DMF), 2-butanone, toluene, and ethyl acetate with mean concentrations of 80.0 ± 1.8, 34.5 ± 0.8, 103.7 ± 2.8, and 26.6 ± 0.7 ppbv, respectively, were identified as the major VOC mixture at all times of the day around the receptor site. As the toxic air pollutant, the concentrations of DMF in air samples were found exceeding the ambient standard despite the path-average effect of OP-FTIR upon concentration levels. The PCA data identified three major emission sources, including PU coating, chemical packaging, and lithographic printing industries. Applying instrumental measurement and statistical modeling, this study has established a systematic approach for locating emission sources. Statistical modeling (PCA) plays an important role in reducing dimensionality of a large measured dataset and identifying underlying emission sources. Instrumental measurement, however, helps verify the outcomes of the statistical modeling. The field study has demonstrated the feasibility of

  17. Locating the sources of an invasive pest, grape phylloxera, using a mitochondrial DNA gene genealogy.

    PubMed

    Downie, D A

    2002-10-01

    Range expansions through human introductions have increased with global commerce and have led to the extinction of native species, alterations in community structure and pest status of the invasive species. Inferring the evolutionary history of invasive species can help to build a firmer footing for management tactics. This study used mitochondrial DNA (mtDNA) sequence comparisons of samples collected from the native and introduced ranges of a pest herbivore of cultivated grapes, grape phylloxera (Daktulosphaira vitifoliae Fitch, Phylloxeridae) to infer the sources and pattern of introductions into worldwide viticulture. Introductions into viticulture from its native North American range first occurred in the mid-19th century. The pattern of spread has suggested a focus of introduction into France, but independent introductions may have occurred elsewhere. The results show that the introduced population represents a limited subsample of the native genetic diversity. The data suggest that most grape phylloxera in viticulture, including all European, have originated in the northeastern USA where the grape species Vitis riparia dominates. There was evidence for independent introductions into South Africa and California. Most California haplotypes were most closely related to native grape phylloxera from the Atlantic Coast on V. vulpina. It is likely that subsequent spread from California into Australia, New Zealand and Peru has occurred. PMID:12296945

  18. Plasma assisted growth of MoO3 films on different substrate locations relative to sublimation source

    NASA Astrophysics Data System (ADS)

    Sharma, Rabindar K.; Saini, Sujit K.; Kumar, Prabhat; Singh, Megha; Reddy, G. B.

    2016-05-01

    In the present paper, we reported the role of substrate locations relative to source on the growth of MoO3 films deposited on Ni coated glass substrates using plasma assisted sublimation process (PASP). According to the XRD and SEM results, substrate location is very crucial factor to control the morphology of MoO3 films and the best nanostructure growth (in terms of alignments and features) is obtained in case of Sample B (in which substrate is placed on source). The structural results point out that all films exhibit only orthorhombic phase of molybdenum oxide (i.e. α-MoO3)but the most preferential growth is recorded in Sample B due to the presence of intense peaks crossponding to only (0 k 0) family of crystal planes (k = 2, 4,6..). The Raman analysis again confirms the orthorhombic nature of MoO3 NFs and details of vibrational bondsin Sample B have been given in the present report. The MoO3 NFs show intense PL emission in wavelength range of 300-700 nm with three peaks located at 415, 490, and 523 nm in accordance to the improved crystallinity in Sample B.

  19. Location and source mechanism of the Karlsruhe earthquake of 24 September 2014

    NASA Astrophysics Data System (ADS)

    Barth, Andreas

    2016-02-01

    On 24 September 2014, a ML 2.3 earthquake occurred southwest of the urban area of Karlsruhe, Germany, which was felt by a few people (maximum intensity I 0 = III). It was the first seismic event in this highly populated area since an I 0 = VII earthquake in 1948. Data of 35 permanent and temporary seismometers were analysed to localise the event and to determine the focal mechanism to compare it to previous seismicity. Restricting the data to P- and S-phases from 18 nearby stations and optimising the local earth model result in an epicentre in the southwest of the city at 48.986°N/8.302°E and in a hypocentral depth of 10 km. To calculate the focal mechanism, 22 P- and 5 SH-polarities were determined that constrain a stable left lateral strike-slip focal mechanism with a minor thrusting component and nodal planes striking NE-SW and NW-SE. The epicentre lies in the vicinity of the I 0 = VII earthquake of 1948. Both events are part of the graben-parallel flower structure beneath the Upper Rhine Graben, parallel to the active Rastatt source zone, which runs 5 km further east and included the epicentre of the 1933 Rastatt I 0 = VII earthquake. The focal mechanisms of the 2014 and 1948 earthquakes show NE-SW striking nodal planes that dip to the southeast. However, for the 1948 event, a normal faulting mechanism was determined earlier. Taking the uncertainty of the epicentre and focal mechanism in 1948 and its fault dimensions into account, both events might have happened on the same fault plane.

  20. Location and source mechanism of the Karlsruhe earthquake of 24 September 2014

    NASA Astrophysics Data System (ADS)

    Barth, Andreas

    2016-07-01

    On 24 September 2014, a ML 2.3 earthquake occurred southwest of the urban area of Karlsruhe, Germany, which was felt by a few people (maximum intensity I 0 = III). It was the first seismic event in this highly populated area since an I 0 = VII earthquake in 1948. Data of 35 permanent and temporary seismometers were analysed to localise the event and to determine the focal mechanism to compare it to previous seismicity. Restricting the data to P- and S-phases from 18 nearby stations and optimising the local earth model result in an epicentre in the southwest of the city at 48.986°N/8.302°E and in a hypocentral depth of 10 km. To calculate the focal mechanism, 22 P- and 5 SH-polarities were determined that constrain a stable left lateral strike-slip focal mechanism with a minor thrusting component and nodal planes striking NE-SW and NW-SE. The epicentre lies in the vicinity of the I 0 = VII earthquake of 1948. Both events are part of the graben-parallel flower structure beneath the Upper Rhine Graben, parallel to the active Rastatt source zone, which runs 5 km further east and included the epicentre of the 1933 Rastatt I 0 = VII earthquake. The focal mechanisms of the 2014 and 1948 earthquakes show NE-SW striking nodal planes that dip to the southeast. However, for the 1948 event, a normal faulting mechanism was determined earlier. Taking the uncertainty of the epicentre and focal mechanism in 1948 and its fault dimensions into account, both events might have happened on the same fault plane.

  1. Shifting primary energy source and NOx emission location with plug-in hybrid vehicles

    NASA Astrophysics Data System (ADS)

    Karman, Deniz

    2011-06-01

    Plug-in hybrid vehicles (PHEVs) present an interesting technological opportunity for using non-fossil primary energy in light duty passenger vehicles, with the associated potential for reducing air pollutant and greenhouse gas emissions, to the extent that the electric power grid is fed by non-fossil sources. This perspective, accompanying the article by Thompson et al (2011) in this issue, will touch on two other studies that are directly related: the Argonne study (Elgowainy et al 2010) and a PhD thesis from Utrecht (van Vliet 2010). Thompson et al (2011) have examined air quality effects in a case where the grid is predominantly fossil fed. They estimate a reduction of 7.42 tons/day of NOx from motor vehicles as a result of substituting electric VMTs for 20% of the light duty gasoline vehicle miles traveled. To estimate the impact of this reduction on air quality they also consider the increases in NOx emissions due to the increased load on electricity generating units. The NOx emission increases are estimated as 4.0, 5.5 and 6.3 tons for the Convenience, Battery and Night charging scenarios respectively. The net reductions are thus in the 1.1-3.4 tons/day range. The air quality modelling results presented show that the air quality impact from a ground-level ozone perspective is favorable overall, and while the effect is stronger in some localities, the difference between the three scenarios is small. This is quite significant and suggests that localization of the NOx emissions to point sources has a more pronounced effect than the absolute reductions achieved. Furthermore it demonstrates that localization of NOx emissions to electricity generating units by using PHEVs in vehicle traffic has beneficial effects for air quality not only by minimizing direct human exposure to motor vehicle emissions, but also due to reduced exposure to secondary pollutants (i.e. ozone). In an electric power grid with a smaller share of fossil fired generating units, the beneficial

  2. Fuel from Wastewater - Harnessing a Potential Energy Source in Canada through the Co-location of Algae Biofuel Production to Sources of Effluent, Heat and CO2

    NASA Astrophysics Data System (ADS)

    Klise, G. T.; Roach, J. D.; Passell, H. D.; Moreland, B. D.; O'Leary, S. J.; Pienkos, P. T.; Whalen, J.

    2010-12-01

    Sandia National Laboratories is collaborating with the National Research Council (NRC) Canada and the National Renewable Energy Laboratory (NREL) to develop a decision-support model that will evaluate the tradeoffs associated with high-latitude algae biofuel production co-located with wastewater, CO2, and waste heat. This project helps Canada meet its goal of diversifying fuel sources with algae-based biofuels. The biofuel production will provide a wide range of benefits including wastewater treatment, CO2 reuse and reduction of demand for fossil-based fuels. The higher energy density in algae-based fuels gives them an advantage over crop-based biofuels as the “production” footprint required is much less, resulting in less water consumed and little, if any conversion of agricultural land from food to fuel production. Besides being a potential source for liquid fuel, algae have the potential to be used to generate electricity through the burning of dried biomass, or anaerobically digested to generate methane for electricity production. Co-locating algae production with waste streams may be crucial for making algae an economically valuable fuel source, and will certainly improve its overall ecological sustainability. The modeling process will address these questions, and others that are important to the use of water for energy production: What are the locations where all resources are co-located, and what volumes of algal biomass and oil can be produced there? In locations where co-location does not occur, what resources should be transported, and how far, while maintaining economic viability? This work is being funded through the U.S. Department of Energy (DOE) Biomass Program Office of Energy Efficiency and Renewable Energy, and is part of a larger collaborative effort that includes sampling, strain isolation, strain characterization and cultivation being performed by the NREL and Canada’s NRC. Results from the NREL / NRC collaboration including specific

  3. Shifting primary energy source and NOx emission location with plug-in hybrid vehicles

    NASA Astrophysics Data System (ADS)

    Karman, Deniz

    2011-06-01

    Plug-in hybrid vehicles (PHEVs) present an interesting technological opportunity for using non-fossil primary energy in light duty passenger vehicles, with the associated potential for reducing air pollutant and greenhouse gas emissions, to the extent that the electric power grid is fed by non-fossil sources. This perspective, accompanying the article by Thompson et al (2011) in this issue, will touch on two other studies that are directly related: the Argonne study (Elgowainy et al 2010) and a PhD thesis from Utrecht (van Vliet 2010). Thompson et al (2011) have examined air quality effects in a case where the grid is predominantly fossil fed. They estimate a reduction of 7.42 tons/day of NOx from motor vehicles as a result of substituting electric VMTs for 20% of the light duty gasoline vehicle miles traveled. To estimate the impact of this reduction on air quality they also consider the increases in NOx emissions due to the increased load on electricity generating units. The NOx emission increases are estimated as 4.0, 5.5 and 6.3 tons for the Convenience, Battery and Night charging scenarios respectively. The net reductions are thus in the 1.1-3.4 tons/day range. The air quality modelling results presented show that the air quality impact from a ground-level ozone perspective is favorable overall, and while the effect is stronger in some localities, the difference between the three scenarios is small. This is quite significant and suggests that localization of the NOx emissions to point sources has a more pronounced effect than the absolute reductions achieved. Furthermore it demonstrates that localization of NOx emissions to electricity generating units by using PHEVs in vehicle traffic has beneficial effects for air quality not only by minimizing direct human exposure to motor vehicle emissions, but also due to reduced exposure to secondary pollutants (i.e. ozone). In an electric power grid with a smaller share of fossil fired generating units, the beneficial

  4. Passive Effluent Diffusion in a Convective Atmospheric Boundary Layer: An Airborne Approach to Locating Sources and Estimating Their Emission Rates

    NASA Astrophysics Data System (ADS)

    Suard, Maxime

    We studied the near field dispersion of natural gas plumes leaking from transmission lines and diffusing in a convective Atmospheric Boundary Layer (ABL), with the intent of providing an aerial system of leak detection and pinpointing, as well as quantitative leak rate estimation. We used high frequency measurements of methane and ethane concentrations on a fixed wing aircraft using high rate spectroscopic gas concentration measurements. We looked for characteristics of the effluent concentration field which can be related to the distance from the effluent source, and developed an empirical approach to effluent source position estimation from airborne effluent concentration measurements. From a mass-balance approach we developed a practical method of effluent leak rate estimation based on airborne effluent concentration measurements. Since gathering experimental data was costly and time-expensive, Large Eddy Simulation (LES) results were also investigated. Results showed that analysis of effluent concentration variability is likely to provide information about the position of the effluent source. The developed leak rate estimation method provided encouraging results showing that such an approach is able to yield relatively accurate leak rate estimates. LES results proved to be very useful as they helped to provide guidelines for experiments as well as to deepen our understanding of the diffusion dynamics of turbulent effluent plumes.

  5. Near-Infrared Image Reconstruction of Newborns' Brains: Robustness to Perturbations of the Source/Detector Location.

    PubMed

    Ahnen, L; Wolf, M; Hagmann, C; Sanchez, S

    2016-01-01

    The brain of preterm infants is the most vulnerable organ and can be severely injured by cerebral ischemia. We are working on a near-infrared imager to early detect cerebral ischemia. During imaging of the brain, movements of the newborn infants are inevitable and the near-infrared sensor has to be able to function on irregular geometries. Our aim is to determine the robustness of the near-infrared image reconstruction to small variations of the source and detector locations. In analytical and numerical simulations, the error estimations for a homogeneous medium agree well. The worst case estimates of errors in reduced scattering and absorption coefficient for distances of r=40 mm are acceptable for a single source-detector pair. The optical properties of an inhomogeneity representing an ischemia are reconstructed correctly within a homogeneous medium, if the error in placement is random. PMID:26782235

  6. Microseismic monitoring of soft-rock landslide: contribution of a 3D velocity model for the location of seismic sources.

    NASA Astrophysics Data System (ADS)

    Floriane, Provost; Jean-Philippe, Malet; Cécile, Doubre; Julien, Gance; Alessia, Maggi; Agnès, Helmstetter

    2015-04-01

    Characterizing the micro-seismic activity of landslides is an important parameter for a better understanding of the physical processes controlling landslide behaviour. However, the location of the seismic sources on landslides is a challenging task mostly because of (a) the recording system geometry, (b) the lack of clear P-wave arrivals and clear wave differentiation, (c) the heterogeneous velocities of the ground. The objective of this work is therefore to test whether the integration of a 3D velocity model in probabilistic seismic source location codes improves the quality of the determination especially in depth. We studied the clay-rich landslide of Super-Sauze (French Alps). Most of the seismic events (rockfalls, slidequakes, tremors...) are generated in the upper part of the landslide near the main scarp. The seismic recording system is composed of two antennas with four vertical seismometers each located on the east and west sides of the seismically active part of the landslide. A refraction seismic campaign was conducted in August 2014 and a 3D P-wave model has been estimated using the Quasi-Newton tomography inversion algorithm. The shots of the seismic campaign are used as calibration shots to test the performance of the different location methods and to further update the 3D velocity model. Natural seismic events are detected with a semi-automatic technique using a frequency threshold. The first arrivals are picked using a kurtosis-based method and compared to the manual picking. Several location methods were finally tested. We compared a non-linear probabilistic method coupled with the 3D P-wave model and a beam-forming method inverted for an apparent velocity. We found that the Quasi-Newton tomography inversion algorithm provides results coherent with the original underlaying topography. The velocity ranges from 500 m.s-1 at the surface to 3000 m.s-1 in the bedrock. For the majority of the calibration shots, the use of a 3D velocity model

  7. Development of a Persistent Reactive Treatment Zone for Containment of Sources Located in Lower-Permeability Strata

    NASA Astrophysics Data System (ADS)

    Marble, J.; Carroll, K. C.; Brusseau, M. L.; Plaschke, M.; Brinker, F.

    2013-12-01

    Source zones located in relatively deep, low-permeability formations provide special challenges for remediation. Application of permeable reactive barriers, in-situ thermal, or electrokinetic methods would be expensive and generally impractical. In addition, the use of enhanced mass-removal approaches based on reagent injection (e.g., ISCO, enhanced-solubility reagents) is likely to be ineffective. One possible approach for such conditions is to create a persistent treatment zone for purposes of containment. This study examines the efficacy of this approach for containment and treatment of contaminants in a lower permeability zone using potassium permanganate (KMnO4) as the reactant. A localized 1,1-dichloroethene (DCE) source zone is present in a section of the Tucson International Airport Area (TIAA) Superfund Site. Characterization studies identified the source of DCE to be located in lower-permeability strata adjacent to the water table. Bench-scale studies were conducted using core material collected from boreholes drilled at the site to measure DCE concentrations and determine natural oxidant demand. The reactive zone was created by injecting ~1.7% KMnO4 solution into multiple wells screened within the lower-permeability unit. The site has been monitored for ~8 years to characterize the spatial distribution of DCE and permanganate. KMnO4 continues to persist at the site, demonstrating successful creation of a long-term reactive zone. Additionally, the footprint of the DCE contaminant plume in groundwater has decreased continuously with time. This project illustrates the application of ISCO as a reactive-treatment system for lower-permeability source zones, which appears to effectively mitigate persistent mass flux into groundwater.

  8. 40 CFR Table 2d to Subpart Zzzz of... - Requirements for Existing Compression Ignition Stationary RICE Located at Area Sources of HAP...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Ignition Stationary RICE Located at Area Sources of HAP Emissions 2d Table 2d to Subpart ZZZZ of Part 63... Stationary RICE Located at Area Sources of HAP Emissions As stated in §§ 63.6600 and 63.6640, you must comply with the following emission and operating limitations for existing compression ignition stationary...

  9. 40 CFR Table 2c to Subpart Zzzz of... - Requirements for Existing Compression Ignition Stationary Rice Located at Major Sources of HAP...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Ignition Stationary Rice Located at Major Sources of HAP Emissions 2c Table 2c to Subpart ZZZZ of Part 63... Stationary Rice Located at Major Sources of HAP Emissions As stated in §§ 63.6600 and 63.6640, you must comply with the following requirements for existing compression ignition stationary RICE: For...

  10. 40 CFR Table 2c to Subpart Zzzz of... - Requirements for Existing Compression Ignition Stationary RICE Located at a Major Source of HAP...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 14 2013-07-01 2013-07-01 false Requirements for Existing Compression Ignition Stationary RICE Located at a Major Source of HAP Emissions and Existing Spark Ignition Stationary RICE â¤500 HP Located at a Major Source of HAP Emissions 2c Table 2c to Subpart ZZZZ of Part 63 Protection of Environment...

  11. Locating sources of surf zone pollution: a mass budget analysis of fecal indicator bacteria at Huntington Beach, California.

    PubMed

    Kim, Joon Ha; Grant, Stanley B; McGee, Charles D; Sanders, Brett F; Largier, John L

    2004-05-01

    The surf zone is the unique environment where ocean meets land and a place of critical ecological, economic, and recreational importance. In the United States, this natural resource is increasingly off-limits to the public due to elevated concentrations of fecal indicator bacteria and other contaminants, the sources of which are often unknown. In this paper, we describe an approach for calculating mass budgets of pollutants in the surf zone from shoreline monitoring data. The analysis reveals that fecal indicator bacteria pollution in the surf zone at several contiguous beaches in Orange County, California, originates from well-defined locations along the shore, including the tidal outlets of the Santa Ana River and Talbert Marsh. Fecal pollution flows into the ocean from the Santa Ana River and Talbert Marsh outlets during ebb tides and from there is transported parallel to the shoreline by wave-driven surf zone currents and/or offshore tidal currents, frequently contaminating >5 km of the surf zone. The methodology developed here for locating and quantifying sources of surf zone pollution should be applicable to a wide array of contaminants and coastal settings. PMID:15180059

  12. Interaural sound pressure level differences associated with sound-source locations in the frontal hemifield of the domestic cat.

    PubMed

    Martin, R L; Webster, W R

    1989-04-01

    Interaural sound pressure level differences (ILDs) associated with a range of sound-source azimuths and elevations in the frontal hemifields of four cats were measured for each of seven pure-tone stimuli ranging in frequency from 2-32 kHz. The overall pattern of ILD across location at each frequency was remarkably similar in all cats. At 2, 4 and 8 kHz the relationships of ILD to azimuth and elevation were generally monotonic with ILD increasing with increasing azimuth. At 12 kHz and above, however, non-monotonic relationships developed and circumscribed regions of particularly large, positive and negative ILDs were apparent. That ILDs associated with many sound-source locations on the near side of the head are negative in sign has not been widely noted in the previous literature. The data obtained in this study were compared with those from previous studies and the acoustical mechanisms likely to have contributed to production of the observed ILDs were considered. Some implications of the data for auditory localization in three-dimensional space were discussed. PMID:2708168

  13. Spatial variability and source apportionment of PM2.5 across multiple sampling locations in southwest China

    NASA Astrophysics Data System (ADS)

    Shi, F.; Xie, S.

    2015-12-01

    The Chengdu Plain, which is located in the west of the Sichuan Basin, is the largest plain and the fastest-growing area in southwest China. The Chengdu Plain is considered one of the hotspot areas in China. The pollution pattern in this area is unique due to the hilly topography, humid and stagnant weather. To investigate the composition and major sources of the ambient PM2.5, a one-year observation was performed at five sites in the Chengdu Plain during August, 2013 to August, 2014. The five sites contained three urban background sites and two rural background sites. Samples were analyzed for major water-soluble ions, organic carbon (OC), element carbon (EC), and trace elements. The Positive Matrix Factorization (PMF) receptor model based on the combined data from five locations was applied to identify and quantify the likely sources. The annual mean mass concentration of PM2.5 in Chengdu Plain was 81 μg·m-3 with the maximum in winter and the minimum in summer. Eight main factors were identified for the PM2.5 fraction: vehicle emission, secondary nitrate, biomass burning and waste incineration emission, secondary sulfate, Mo-related manufacturing, fugitive dust, coal combustion and industry pollution. The five-site annual mean contributions of each source were 13%, 19%, 9%, 25%, 2%, 13%, 9% and 10%,respectively, to PM2.5, while exhibiting large spatial variability. The contribution of secondary sulfate to the PM2.5 mass was largest at all sites, indicating severe secondary pollution in the region. Biomass burning and waste incineration emission made larger proportion at rural sites than that of urban sites, while the vehicle emission was larger at urban sites. The Enrichment factors for Cd, Zn, Pb, As, Cu and Mo in PM2.5 were larger than 100 indicated that those elements were largely from anthropogenic origins. Cd, As and Cu can mainly originate from nonferrous metal industry, while Mo may mainly generated from ferromolybdenum and Mo powder manufacture. The

  14. Consumption of added sugars among US children and adults by food purchase location and food source123

    PubMed Central

    Drewnowski, Adam; Rehm, Colin D

    2014-01-01

    Background: The proposed changes to the Nutrition Facts Label by the US Food and Drug Administration will include information on added sugars for the first time. Objective: The objective was to evaluate the sources of added sugars in the diets of a representative sample of US children and adults by food purchase location and food source (eg, food group). Design: This cross-sectional study among 31,035 children, adolescents, and adults aged ≥6 y from the 2003–2004, 2005–2006, 2007–2008, and 2009–2010 NHANES used data from a 24-h dietary recall to evaluate consumption of added sugars. Food locations of origin were identified as stores (supermarket or grocery store), quick-service restaurants/pizza (QSRs), full-service restaurants (FSRs), schools, and others (eg, vending machines or gifts). Added sugars consumption by food purchase location was evaluated by age, family income-to-poverty ratio, and race-ethnicity. Food group sources of added sugars were identified by using the National Cancer Institute food categories. Results: Added sugars accounted for ∼14.1% of total dietary energy. Between 65% and 76% of added sugars came from stores, 6% and 12% from QSRs, and 4% and 6% from FSRs, depending on age. Older adults (aged ≥51 y) obtained a significantly greater proportion of added sugars from stores than did younger adults. Lower-income adults obtained a significantly greater proportion of added sugars from stores than did higher-income adults. Intake of added sugars did not vary by family income among children/adolescents. Soda and energy and sports drinks were the largest food group sources of added sugars (34.4%), followed by grain desserts (12.7%), fruit drinks (8.0%), candy (6.7%), and dairy desserts (5.6%). Conclusions: Most added sugars came from foods obtained from stores. The proposed changes to the Nutrition Facts Label should capture the bulk of added sugars in the US food supply, which suggests that the recommended changes have the potential to

  15. Sodium Intakes of US Children and Adults from Foods and Beverages by Location of Origin and by Specific Food Source

    PubMed Central

    Drewnowski, Adam; Rehm, Colin D.

    2013-01-01

    Sodium intakes, from foods and beverages, of 22,852 persons in the National Health and Nutrition Examination Surveys (NHANES 2003–2008) were examined by specific food source and by food location of origin. Analyses were based on a single 24-h recall. Separate analyses were conducted for children (6–11 years of age), adolescents (12–19), and adults (20–50 and ≥51 years). Grouping of like foods (e.g., food sources) used a scheme proposed by the National Cancer Institute, which divides foods/beverages into 96 food subgroups (e.g., pizza, yeast breads or cold cuts). Food locations of origin were stores (e.g., grocery, convenience and specialty stores), quick-service restaurant/pizza (QSR), full-service restaurant (FSR), school, or other. Food locations of sodium were also evaluated by race/ethnicity amongst adults. Stores provided between 58.1% and 65.2% of dietary sodium, whereas QSR and FSR together provided between 18.9% and 31.8% depending on age. The proportion of sodium from QSR varied from 10.1% to 19.9%, whereas that from FSR varied from 3.4% to 13.3%. School meals provided 10.4% of sodium for 6–11 year olds and 6.0% for 12–19 year olds. Pizza from QSR, the top away from home food item, provided 5.4% of sodium in adolescents. QSR pizza, chicken, burgers and Mexican dishes combined provided 7.8% of total sodium in adult diets. Most sodium came from foods purchased in stores. Food manufacturers, restaurants, and grocery stores all have a role to play in reducing the amount of sodium in the American diet. PMID:23760055

  16. Location of Body Wave Microseism Sources Using Three-Component Data From a Large Aperture Seismic Array in China

    NASA Astrophysics Data System (ADS)

    Liu, Q.; Koper, K. D.; Burlacu, R.; Ni, S.; Wang, F.

    2015-12-01

    From September 2013 through October 2014 up to 100 Guralp CMG-3 broadband seismometers were deployed in the WT-Array (WTA) in northwest China. The aperture of WTA is about 700 km, with an average station spacing of approximately 50 km. Here, we process continuous, three-component WTA data to detect and locate body wave microseism sources in four distinct period bands: 1.0-2.5 s, 2.5-5 s, 5-10 s, and 10-20 s. We back-project vertical component data through a 1D reference Earth model (AK135) to a global grid of hypothetical source locations, assuming P-wave (30o-90o), PP-wave (60o-180o), and S-wave (30o-75o) propagation. At the same time, we rotate the horizontals and back-project the radial and transverse components of the wavefield. For each frequency band, grid point, and assumed origin time, the array power is calculated from the amplitude of a windowed, filtered, and tapered time domain beam constructed with fourth-root stacking. We find strong P-wave and S-wave noise sources in the North Pacific and North Atlantic Oceans. Shorter period sources (2.5-5 s) are mainly observed in the North Pacific Ocean, while both short and long period (2.5-20 s) sources are observed in the North Atlantic Ocean. Median power plots for each month during September 2013 through October 2014 show distinct seasonal variations. The energy peaks in the North Atlantic are visible from November to March and strong energy is also observed in the North Pacific from October to April. We also observe PP-waves in the Southern Ocean, especially for May-August 2014. Using classical f-k analysis and plane-wave propagation, we are able to confirm the back-projection results. To improve our understanding of body wave microseism generation, we compare the observed P, S, and PP wave microseism locations with the predictions of significant wave height and wave-wave interactions derived from the WAVEWATCH III ocean model.From September 2013 through October 2014 up to 100 Guralp CMG-3 broadband

  17. Locating sources of hazardous gas emissions using dual pollution rose plots and open path Fourier transform infrared spectroscopy.

    PubMed

    Sung, Lung-Yu; Shie, Ruei-Hou; Lu, Chia-Jung

    2014-01-30

    A new approach employing two pollution rose plots to locate the sources of multiple hazardous gas emissions was proposed and tested in an industrial area. The data used for constructing the pollution rose plots were obtained from two side-by-side measurements of open-path Fourier Transform Infrared (OP-FTIR) spectrometers during one week of continuous analysis on the rooftop of a semiconductor plant. Hazardous gases such as CF4, C2F6, CH3OH, NH3, NO2, and SF6 were found and quantified at the ppb level by both OP-FTIR measurement sites. The data of the top 20% highest concentrations and associated wind directions were used to construct the pollution rose plots. Pollution source probability contours for each compound were constructed using the probability-product of directional probability from two pollution rose plots. Hot spots for SF6, CF4, NO2, and C2F6 pointed to the stack area of the plant, but the sources of CH3OH and NH3 were found outside of this plant. The influences of parameters for this approach such as the variation in wind direction, lower limit concentration threshold and the nearby buildings were discussed. PMID:24333712

  18. Recovery the release history and source location of a pollutant in groundwater using data collected in laboratory

    NASA Astrophysics Data System (ADS)

    Zanini, A.; Cupola, F.

    2013-12-01

    This work shows the application of an innovative procedure that is able to simultaneously identify the release history and the source location of a pollutant injection in groundwater using a dataset obtained experimentally. The methodology follows a geostatistical approach and it requires a preliminary delineation of a probably source area. The dataset was provided through an experimental installation developed at the hydraulic laboratory of the University of Parma (DICATeA). The equipment represents a 2-D unconfined aquifer controlled through two constant head levels (upstream and downstream); it consists of a Plexiglas sandbox filled with a porous medium (1 mm glass beads). An injector was placed inside the porous medium and sodium fluorescein salt was used as tracer during the tests. The standard test consists of releasing a constant and known concentration with a variable flow rate. The injection rate and the mean flow rate inside the sandbox are stored by means of a data acquisition system, meanwhile the concentration distribution inside the sandbox is observed through the processing of side wall images collected by means of a digital camera. The digital camera and the sandbox are placed in a dark room lightened by blue light in order to excite the fluorescein and easily evaluate the concentration distribution. A Matlab routine was developed to cut and to correct images by a projective transformation in order to obtain pictures with same size and orientation. Each pixel of the image has known coordinates on the sandbox. After a calibration process, the relationships between the luminosity of the emitted fluorescence and the tracer concentration have been identified in each pixel of the picture and consequently in each point of the domain. Initially a series of simple tests (with constant injection) were carried out with the aim at validating the experimental equipment comparing the observed data to those collected through the images, such as mass balance or

  19. Identification of Unknown Interface Locations in a Source/Shield System Using the Mesh Adaptive Direct Search Method

    SciTech Connect

    Armstrong, Jerawan C.; Favorite, Jeffrey A.

    2012-06-20

    The Levenberg-Marquardt (or simply Marquardt) and differential evolution (DE) optimization methods were recently applied to solve inverse transport problems. The Marquardt method is fast but convergence of the method is dependent on the initial guess. While it has been shown to work extremely well at finding an optimum independent of the initial guess, the DE method does not provide a global optimal solution in some problems. In this paper, we apply the Mesh Adaptive Direct Search (MADS) algorithm to solve the inverse problem of material interface location identification in one-dimensional spherical radiation source/shield systems, and we compare the results obtained by MADS to those obtained by Levenberg-Marquardt and DE.

  20. Joint inversion of seismic velocities and source location without rays using the truncated Newton and the adjoint-state method

    NASA Astrophysics Data System (ADS)

    Virieux, J.; Bretaudeau, F.; Metivier, L.; Brossier, R.

    2013-12-01

    Simultaneous inversion of seismic velocities and source parameters have been a long standing challenge in seismology since the first attempts to mitigate trade-off between very different parameters influencing travel-times (Spencer and Gubbins 1980, Pavlis and Booker 1980) since the early development in the 1970s (Aki et al 1976, Aki and Lee 1976, Crosson 1976). There is a strong trade-off between earthquake source positions, initial times and velocities during the tomographic inversion: mitigating these trade-offs is usually carried empirically (Lemeur et al 1997). This procedure is not optimal and may lead to errors in the velocity reconstruction as well as in the source localization. For a better simultaneous estimation of such multi-parametric reconstruction problem, one may take benefit of improved local optimization such as full Newton method where the Hessian influence helps balancing between different physical parameter quantities and improving the coverage at the point of reconstruction. Unfortunately, the computation of the full Hessian operator is not easily computed in large models and with large datasets. Truncated Newton (TCN) is an alternative optimization approach (Métivier et al. 2012) that allows resolution of the normal equation H Δm = - g using a matrix-free conjugate gradient algorithm. It only requires to be able to compute the gradient of the misfit function and Hessian-vector products. Traveltime maps can be computed in the whole domain by numerical modeling (Vidale 1998, Zhao 2004). The gradient and the Hessian-vector products for velocities can be computed without ray-tracing using 1st and 2nd order adjoint-state methods for the cost of 1 and 2 additional modeling step (Plessix 2006, Métivier et al. 2012). Reciprocity allows to compute accurately the gradient and the full Hessian for each coordinates of the sources and for their initial times. Then the resolution of the problem is done through two nested loops. The model update Δm is

  1. Lunar Pickup Ions Observed by ARTEMIS: Spatial and Temporal Distribution and Constraints on Species and Source Locations

    NASA Technical Reports Server (NTRS)

    Halekas, Jasper S.; Poppe, A. R.; Delory, G. T.; Sarantos, M.; Farrell, W. M.; Angelopoulos, V.; McFadden, J. P.

    2012-01-01

    ARTEMIS observes pickup ions around the Moon, at distances of up to 20,000 km from the surface. The observed ions form a plume with a narrow spatial and angular extent, generally seen in a single energy/angle bin of the ESA instrument. Though ARTEMIS has no mass resolution capability, we can utilize the analytically describable characteristics of pickup ion trajectories to constrain the possible ion masses that can reach the spacecraft at the observation location in the correct energy/angle bin. We find that most of the observations are consistent with a mass range of approx. 20-45 amu, with a smaller fraction consistent with higher masses, and very few consistent with masses below 15 amu. With the assumption that the highest fluxes of pickup ions come from near the surface, the observations favor mass ranges of approx. 20-24 and approx. 36-40 amu. Although many of the observations have properties consistent with a surface or near-surface release of ions, some do not, suggesting that at least some of the observed ions have an exospheric source. Of all the proposed sources for ions and neutrals about the Moon, the pickup ion flux measured by ARTEMIS correlates best with the solar wind proton flux, indicating that sputtering plays a key role in either directly producing ions from the surface, or producing neutrals that subsequently become ionized.

  2. Source contributions to PM2.5 and PM10 at an urban background and a street location

    NASA Astrophysics Data System (ADS)

    Keuken, M. P.; Moerman, M.; Voogt, M.; Blom, M.; Weijers, E. P.; Röckmann, T.; Dusek, U.

    2013-06-01

    The contribution of regional, urban and traffic sources to PM2.5 and PM10 in an urban area was investigated in this study. The chemical composition of PM2.5 and PM10 was measured over a year at a street location and up- and down-wind of the city of Rotterdam, the Netherlands. The 14C content in EC and OC concentrations was also determined, to distinguish the contribution from "modern" carbon (e.g., biogenic emissions, biomass burning and wildfires) and fossil fuel combustion. It was concluded that the urban background of PM2.5 and PM10 is dominated by the regional background, and that primary and secondary PM emission by urban sources contribute less than 15%. The 14C analysis revealed that 70% of OC originates from modern carbon and 30% from fossil fuel combustion. The corresponding percentages for EC are, respectively 17% and 83%. It is concluded that in particular the urban population living in street canyons with intense road traffic has potential health risks. This is due to exposure to elevated concentrations of a factor two for EC from exhaust emissions in PM2.5 and a factor 2-3 for heavy metals from brake and tyre wear, and re-suspended road dust in PM10. It follows that local air quality management may focus on local measures to street canyons with intense road traffic.

  3. Identifying sources of ozone to three rural locations in Nevada, USA, using ancillary gas pollutants, aerosol chemistry, and mercury.

    PubMed

    Miller, Matthieu B; Fine, Rebekka; Pierce, Ashley M; Gustin, Mae S

    2015-10-15

    Ozone (O3) is a secondary air pollutant of long standing and increasing concern for environmental and human health, and as such, the US Environmental Protection Agency will revise the National Ambient Air Quality Standard of 75 ppbv to ≤ 70 ppbv. Long term measurements at the Great Basin National Park (GBNP) indicate that O3 in remote areas of Nevada will exceed a revised standard. As part of the Nevada Rural Ozone Initiative, measurements of O3 and other air pollutants were made at 3 remote sites between February 2012 and March 2014, GBNP, Paradise Valley (PAVA), and Echo Peak (ECHO). Exceptionally high concentrations of each air pollutant were defined relative to each site as mixing ratios that exceeded the 90th percentile of all hourly data. Case studies were analyzed for all periods during which mean daily O3 exceeded the 90th percentile concurrently with a maximum 8-h average (MDA8) O3 that was "exceptionally high" for the site (65 ppbv at PAVA, 70 ppbv at ECHO and GBNP), and of potential regulatory significance. An MDA8 ≥ 65 ppbv occurred only five times at PAVA, whereas this occurred on 49 and 65 days at GBNP and ECHO, respectively. The overall correlation between O3 and other pollutants was poor, consistent with the large distance from significant primary emission sources. Mean CO at these locations exceeded concentrations reported for background sites in 2000. Trajectory residence time calculations and air pollutant concentrations indicate that exceedances at GBNP and ECHO were promoted by air masses originating from multiple sources, including wildfires, transport of pollution from southern California and the marine boundary layer, and transport of Asian pollution plumes. Results indicate that the State of Nevada will exceed a revised O3 standard due to sources that are beyond their control. PMID:25957787

  4. Fibre intake and incident colorectal cancer depending on fibre source, sex, tumour location and Tumour, Node, Metastasis stage.

    PubMed

    Vulcan, Alexandra; Brändstedt, Jenny; Manjer, Jonas; Jirström, Karin; Ohlsson, Bodil; Ericson, Ulrika

    2015-09-28

    Studies on fibre intake and incident colorectal cancer (CRC) indicate inverse associations. Differences by tumour stage have not been examined. We examined associations between fibre intake and its sources, and incidental CRC. Separate analyses were carried out on the basis of sex, tumour location and the Tumour, Node, Metastasis (TNM) classification. The Malmö Diet and Cancer Study is a population-based cohort study, including individuals aged 45-74 years. Dietary data were collected through a modified diet history method. The TNM classification was obtained from pathology/clinical records and re-evaluated. Among 27 931 individuals (60% women), we found 728 incident CRC cases during 428 924 person-years of follow-up. Fibre intake was inversely associated with CRC risk (P(trend) = 0.026). Concerning colon cancer, we observed borderline interaction between fibre intake and sex (P = 0.052) and significant protective association restricted to women (P(trend) = 0.013). Intake of fruits and berries was inversely associated with colon cancer in women (P(trend) = 0.022). We also observed significant interactions between intakes of fibre (P = 0.048) and vegetables (P = 0.039) and sex on rectal cancer, but no significant associations were seen between intake of fibre, or its sources, in either of the sexes. Except for inverse associations between intake of fibre-rich cereal products and N0- and M0-tumours, we did not observe significant associations with different TNM stages. Our findings suggest different associations between fibre intake and CRC depending on sex, tumour site and fibre source. High fibre intake, especially from fruits and berries, may, above all, prevent tumour development in the colon in women. No clear differences by TNM classification were detected. PMID:26281852

  5. Photochemical parameters of atmospheric source gases: accurate determination of OH reaction rate constants over atmospheric temperatures, UV and IR absorption spectra

    NASA Astrophysics Data System (ADS)

    Orkin, V. L.; Khamaganov, V. G.; Martynova, L. E.; Kurylo, M. J.

    2012-12-01

    The emissions of halogenated (Cl, Br containing) organics of both natural and anthropogenic origin contribute to the balance of and changes in the stratospheric ozone concentration. The associated chemical cycles are initiated by the photochemical decomposition of the portion of source gases that reaches the stratosphere. Reactions with hydroxyl radicals and photolysis are the main processes dictating the compound lifetime in the troposphere and release of active halogen in the stratosphere for a majority of halogen source gases. Therefore, the accuracy of photochemical data is of primary importance for the purpose of comprehensive atmospheric modeling and for simplified kinetic estimations of global impacts on the atmosphere, such as in ozone depletion (i.e., the Ozone Depletion Potential, ODP) and climate change (i.e., the Global Warming Potential, GWP). The sources of critically evaluated photochemical data for atmospheric modeling, NASA/JPL Publications and IUPAC Publications, recommend uncertainties within 10%-60% for the majority of OH reaction rate constants with only a few cases where uncertainties lie at the low end of this range. These uncertainties can be somewhat conservative because evaluations are based on the data from various laboratories obtained during the last few decades. Nevertheless, even the authors of the original experimental works rarely estimate the total combined uncertainties of the published OH reaction rate constants to be less than ca. 10%. Thus, uncertainties in the photochemical properties of potential and current atmospheric trace gases obtained under controlled laboratory conditions still may constitute a major source of uncertainty in estimating the compound's environmental impact. One of the purposes of the presentation is to illustrate the potential for obtaining accurate laboratory measurements of the OH reaction rate constant over the temperature range of atmospheric interest. A detailed inventory of accountable sources of

  6. Sources of Caffeine in Diets of US Children and Adults: Trends by Beverage Type and Purchase Location

    PubMed Central

    Drewnowski, Adam; Rehm, Colin D.

    2016-01-01

    New sources of caffeine, besides coffee and tea, have been introduced into the US food supply. Data on caffeine consumption age and purchase location can help guide public health policy. National Health and Nutrition Examination Surveys (NHANES) were used to estimate population-level caffeine intakes, using data from 24-h dietary recall. First, caffeine intakes by age-group and beverage type were estimated using the most recent 2011–2012 data (n = 7456). Second, fourteen years trends in caffeine consumption, overall and by beverage type, were evaluated for adults and children. Trend analyses were conducted by age groups. Last, trends in caffeine intakes by purchase location and beverage type were estimated. In 2011–2012, children aged four to eight years consumed the least caffeine (15 mg/day), and adults aged 51–70 years consumed the most (213 mg/day). The population mean (age ≥ four years) was 135 mg/day, driven largely by coffee (90 mg/day), tea (25 mg/day), and soda (21 mg/day). For the 14–19 years and 20–34 years age-groups, energy drinks contributed 6 mg/day (9.9%) and 5 mg/day (4.5%), respectively. The bulk of caffeine came from store-bought coffee and tea. Among both children and adults combined, caffeine intakes declined from 175 mg/day (1999–2000) to 142 mg/day (2011–2012), largely driven by a drop in caffeine from soda (41 mg/day to 21 mg/day). Store-bought coffee and tea remain principal drivers of caffeine intake in the US. Sodas and energy drinks make minor contributions to overall caffeine intakes. PMID:26978391

  7. Sources of Caffeine in Diets of US Children and Adults: Trends by Beverage Type and Purchase Location.

    PubMed

    Drewnowski, Adam; Rehm, Colin D

    2016-01-01

    New sources of caffeine, besides coffee and tea, have been introduced into the US food supply. Data on caffeine consumption age and purchase location can help guide public health policy. National Health and Nutrition Examination Surveys (NHANES) were used to estimate population-level caffeine intakes, using data from 24-h dietary recall. First, caffeine intakes by age-group and beverage type were estimated using the most recent 2011-2012 data (n = 7456). Second, fourteen years trends in caffeine consumption, overall and by beverage type, were evaluated for adults and children. Trend analyses were conducted by age groups. Last, trends in caffeine intakes by purchase location and beverage type were estimated. In 2011-2012, children aged four to eight years consumed the least caffeine (15 mg/day), and adults aged 51-70 years consumed the most (213 mg/day). The population mean (age ≥ four years) was 135 mg/day, driven largely by coffee (90 mg/day), tea (25 mg/day), and soda (21 mg/day). For the 14-19 years and 20-34 years age-groups, energy drinks contributed 6 mg/day (9.9%) and 5 mg/day (4.5%), respectively. The bulk of caffeine came from store-bought coffee and tea. Among both children and adults combined, caffeine intakes declined from 175 mg/day (1999-2000) to 142 mg/day (2011-2012), largely driven by a drop in caffeine from soda (41 mg/day to 21 mg/day). Store-bought coffee and tea remain principal drivers of caffeine intake in the US. Sodas and energy drinks make minor contributions to overall caffeine intakes. PMID:26978391

  8. Location of and landing on a source of human body odour by female Culex quinquefasciatus in still and moving air

    PubMed Central

    LACEY, EMERSON S.; CARDÉ, RING T.

    2014-01-01

    The orientation to and landing on a source of human odour by female Culex quinquefasciatus Say (Diptera: Culicidae) is observed in a wind tunnel without an airflow or with a laminar airflow of 0.2 m s-1. Odours from human feet are collected by ‘wearing’ clean glass beads inside a stocking and presenting beads in a Petri dish in a wind tunnel. Mosquitoes are activated by brief exposure to a 1 L min-1 jet of 4% CO2 positioned 10 cm from the release cage. In moving air at 0.2 m s-1, a mean of 3.45 ± 0.49 landings are observed in 10 min trials (5 mosquitoes per trial), whereas 6.50 ± 0.96 landings are recorded in still air. Furthermore, 1.45 ± 0.31mosquitoes are recorded on beads at any one time in moving air (a measure of individuals landing versus one landing multiple times) compared to 3.10 ± 0.31 in still air. Upwind flight to beads in moving air is demonstrated by angular headings of flight immediately prior to landing, whereas approaches to beads in still air are oriented randomly. The mean latency until first landing is 226.7 ± 17.98 s in moving air compared to 122.5 ± 24.18 in still air. Strategies used to locate a prospective host at close range in still air are considered. PMID:26472918

  9. VLBI FOR GRAVITY PROBE B. VI. THE ORBIT OF IM PEGASI AND THE LOCATION OF THE SOURCE OF RADIO EMISSION

    SciTech Connect

    Ransom, R. R.; Bartel, N.; Bietenholz, M. F.; Lebach, D. E.; Ratner, M. I.; Shapiro, I. I.; Lestrade, J.-F.

    2012-07-01

    We present a physical interpretation for the locations of the sources of radio emission in IM Pegasi (IM Peg, HR 8703), the guide star for the NASA/Stanford relativity mission Gravity Probe B. This emission is seen in each of our 35 epochs of 8.4 GHz very long baseline interferometry observations taken from 1997 to 2005. We found that the mean position of the radio emission is at or near the projected center of the primary to within about 27% of its radius, identifying this active star as the radio emitter. The positions of the radio brightness peaks are scattered across the disk of the primary and slightly beyond, preferentially along an axis with position angle, P.A. = -38 Degree-Sign {+-} 8 Degree-Sign , which is closely aligned with the sky projections of the orbit normal (P.A. = -49.{sup 0}5 {+-} 8.{sup 0}6) and the expected spin axis of the primary. Comparison with simulations suggests that brightness peaks are 3.6{sup +0.4}{sub -0.7} times more likely to occur (per unit surface area) near the pole regions of the primary (latitude, |{lambda}| {>=} 70 Degree-Sign ) than near the equator (|{lambda}| {<=} 20 Degree-Sign ), and to also occur close to the surface with {approx}2/3 of them at altitudes not higher than 25% of the radius of the primary.

  10. Two reduced form air quality modeling techniques for rapidly calculating pollutant mitigation potential across many sources, locations and precursor emission types

    NASA Astrophysics Data System (ADS)

    Foley, Kristen M.; Napelenok, Sergey L.; Jang, Carey; Phillips, Sharon; Hubbell, Bryan J.; Fulcher, Charles M.

    2014-12-01

    Due to the computational cost of running regional-scale numerical air quality models, reduced form models (RFM) have been proposed as computationally efficient simulation tools for characterizing the pollutant response to many different types of emission reductions. The U.S. Environmental Protection Agency has developed two types of reduced form models based upon simulations of the Community Multiscale Air Quality (CMAQ) modeling system. One is based on statistical response surface modeling (RSM) techniques using a multidimensional kriging approach to approximate the nonlinear chemical and physical processes. The second approach is based on using sensitivity coefficients estimated with the Decoupled Direct Method in 3 dimensions (CMAQ-DDM-3D) in a Taylor series approximation for the nonlinear response of the pollutant concentrations to changes in emissions from specific sectors and locations. Both types of reduced form models are used to estimate the changes in O3 and PM2.5 across space associated with emission reductions of NOx and SO2 from power plants and other sectors in the eastern United States. This study provides a direct comparison of the RSM- and DDM-3D-based tools in terms of: computational cost, model performance against brute force runs, and model response to changes in emission inputs. For O3, the DDM-3D RFM had slightly better performance on average for low to moderate emission cuts compared to the kriging-based RSM, but over-predicted O3 disbenefits from cuts to mobile source NOx in very urban areas. The RSM approach required more up-front computational cost and produced some spurious O3 increases in response to reductions in power plant emissions. However the RSM provided more accurate predictions for PM2.5 and for predictions of very large emission cuts (e.g. -60 to -90%). This comparison indicates that there are some important differences in the output of the two approaches that should be taken under consideration when interpreting results for a

  11. Directionality of ambient noise on the Juan de Fuca plate: implications for source locations of the primary and secondary microseisms

    NASA Astrophysics Data System (ADS)

    Tian, Ye; Ritzwoller, Michael H.

    2015-04-01

    Based on cross-correlations of ambient seismic noise computed using 61 ocean bottom seismometers (OBSs) within the Juan de Fuca (JdF) plate from the Cascadia Initiative experiment and 42 continental stations near the coast of the western United States, we investigate the locations of generation of the primary (11-20 s period) and secondary (5-10 s period) microseisms in the northern Pacific Ocean by analysing the directionality and seasonality of the microseism (Rayleigh wave) signals received in this region. We conclude that (1) the ambient noise observed across the array is much different in the primary and secondary microseism bands, both in its azimuthal content and seasonal variation. (2) The principal secondary microseism signals propagate towards the east, consistent with their generation in deep waters of the North Pacific, perhaps coincident both with the region of observed body wave excitation and the predicted wave-wave interaction region from recent studies. (3) The primary microseism, as indicated by observations of the azimuthal dependence of the fundamental mode Rayleigh wave as well as observations of precursory arrivals, derives significantly from the shallow waters of the eastern Pacific near to the JdF plate but also has a component generated at greater distance of unknown origin. (4) These observations suggest different physical mechanisms for generating the two microseisms: the secondary microseisms are likely to be generated by non-linear wave-wave interaction over the deep Pacific Ocean, while the primary microseism may couple directly into the solid earth locally in shallow waters from ocean gravity waves. (5) Above 5 s period, high quality empirical Green's functions are observed from cross-correlations between deep water OBSs and continental stations, which illustrates that microseisms propagate efficiently from either deep or shallow water source regions onto the continent and are well recorded by continental seismic stations.

  12. FORTRAN codes to implement enhanced local wave number technique to determine the depth and location and shape of the causative source using magnetic anomaly

    NASA Astrophysics Data System (ADS)

    Agarwal, B. N. P.; Srivastava, Shalivahan

    2008-12-01

    The total field magnetic anomaly is analyzed to compute the depth and location and geometry of the causative source using two FORTRAN source codes, viz., FRCON1D and ELW. No assumption on the nature of source geometry, susceptibility contrast, etc. has been made. The source geometry is estimated by computing the structural index from previously determined depth and location. A detailed procedure is outlined for using these codes through a theoretical anomaly. The suppression of high-frequency noise in the observed data is tackled by designing a box-car window with cosine termination. The termination criterion is based on the peak position of the derivative operator computed for a pre-assumed depth of a shallow source below which the target is situated. The applicability of these codes has been demonstrated by analyzing a total field aeromagnetic anomaly of the Matheson area of northern Ontario, Canada.

  13. Regional location in western China

    SciTech Connect

    Cogbill, A.H.; Steck, L.K.

    1996-10-01

    Accurately locating seismic events in western China using only regional seismic stations is a challenge. Not only is the number of seismic stations available for locating events small, but most stations available to researchers are often over 10{degree} distant. Here the authors describe the relocation, using regional stations, of both nuclear and earthquake sources near the Lop Nor test site in western China. For such relocations, they used the Earthquake Data Reports provided by the US Geological Survey (USGS) for the reported travel times. Such reports provide a listing of all phases reported to the USGS from stations throughout the world, including many stations in the People`s Republic of China. LocSAT was used as the location code. The authors systematically relocated each event int his study several times, using fewer and fewer stations at reach relocation, with the farther stations being eliminated at each step. They found that location accuracy, judged by comparing solutions from few stations to the solution provided using all available stations, remained good typically until fewer than seven stations remained.With a good station distribution, location accuracy remained surprisingly good (within 7 km) using as few as 3 stations. Because these relocations were computed without good station corrections and without source-specific station corrections (that is, path corrections), they believe that such regional locations can be substantially improved, largely using static station corrections and source-specific station corrections, at least in the Lop nor area, where sources have known locations. Elsewhere in China, one must rely upon known locations of regionally-recorded explosions. Locating such sources is clearly one of the major problems to be overcome before one can provide event locations with any assurance from regional stations.

  14. Finding of No Significant Impact and Final Environmental Assessment for the Future Location of Heat Source/Radioisotope Power System Assembly and Testing and Operations Currently Located at the Mound Site

    SciTech Connect

    N /A

    2002-08-30

    The U.S. Department of Energy (the Department) has completed an Environmental Assessment for the Future Location of the Heat Source/Radioisotope Power System Assembly and Test. Operations Currently Located at the Mound Site. Based on the analysis in the environmental assessment, the Department has determined that the proposed action, the relocation of the Department's heat source and radioisotope power system operations, does not constitute a major Federal action significantly affecting the quality of the human environment within the meaning of the ''National Environmental Policy Act'' of 1969 (NEPA). Therefore, the preparation of an Environmental Impact Statement is not required, and the Department is issuing this Finding of No Significant Impact (FONSI).

  15. LOCATING NEARBY SOURCES OF AIR POLLUTION BY NONPARAMETRIC REGRESSION OF ATMOSPHERIC CONCENTRATIONS ON WIND DIRECTION. (R826238)

    EPA Science Inventory

    The relationship of the concentration of air pollutants to wind direction has been determined by nonparametric regression using a Gaussian kernel. The results are smooth curves with error bars that allow for the accurate determination of the wind direction where the concentrat...

  16. Exosat observations of the 5 March 1979 gamma-ray burst source location (GBS 0526-66)

    NASA Technical Reports Server (NTRS)

    Rothschild, R. E.; Staubert, R.; Brinkmann, W.; Pedersen, H.; Parmar, A. N.

    1987-01-01

    A two day observation of the March 5, 1979 gamma-ray burst location (GBS 0526-66) with the European X-ray satellite Exosat is reported. These observations were performed on December 30, 1984 and January 3, 1985 in coordination with a worldwide burst watch of this location by a variety of instruments sensitive in the optical, radio, and X-ray wavelength ranges. No bursts were seen by Exosat.

  17. Source locations of teleseismic P, SV, and SH waves observed in microseisms recorded by a large aperture seismic array in China

    NASA Astrophysics Data System (ADS)

    Liu, Qiaoxia; Koper, Keith D.; Burlacu, Relu; Ni, Sidao; Wang, Fuyun; Zou, Changqiao; Wei, Yunhao; Gal, Martin; Reading, Anya M.

    2016-09-01

    Transversely polarized seismic waves are routinely observed in ambient seismic energy across a wide range of periods, however their origin is poorly understood because the corresponding source regions are either undefined or weakly constrained, and nearly all models of microseism generation incorporate a vertically oriented single force as the excitation mechanism. To better understand the origin of transversely polarized energy in the ambient seismic wavefield we make the first systematic attempt to locate the source regions of teleseismic SH waves observed in microseismic (2.5-20 s) noise. We focus on body waves instead of surface waves because the source regions can be constrained in both azimuth and distance using conventional array techniques. To locate microseismic sources of SH waves (as well as SV and P waves) we continuously backproject the vertical, radial, and transverse components of the ambient seismic wavefield recorded by a large-aperture array deployed in China during 2013-2014. As expected, persistent P wave sources are observed in the North Atlantic, North Pacific, and Indian Oceans, mainly at periods of 2.5-10 s, in regions with the strong ocean wave interactions needed to produce secondary microseisms. SV waves are commonly observed to originate from locations indistinguishable from the P wave sources, but with smaller signal-to-noise ratios. We also observe SH waves with about half or less the signal-to-noise ratio of SV waves. SH source regions are definitively located in deep water portions of the Pacific, away from the sloping continental shelves that are thought to be important for the generation of microseismic Love waves, but nearby regions that routinely generate teleseismic P waves. The excitation mechanism for the observed SH waves may therefore be related to the interaction of P waves with small-wavelength bathymetric features, such as seamounts and basins, through some sort of scattering process.

  18. Acoustic Emission tomography based on simultaneous algebraic reconstruction technique to visualize the damage source location in Q235B steel plate

    NASA Astrophysics Data System (ADS)

    Jiang, Yu; Xu, Feiyun; Xu, Bingsheng

    2015-12-01

    Acoustic Emission (AE) tomography based on Simultaneous Algebraic Reconstruction Technique (SART), which combines the traditional location algorithm with the SART algorithm by using AE events as its signal sources, is a new visualization method for inspecting and locating the internal damages in the structure. In this paper, the proposed method is applied to examine and visualize two man-made damage source locations in the Q235B steel plate to validate its effectiveness. Firstly, the Q235B steel plate with two holes specimen is fabricated and the pencil lead break (PLB) signal is taken as the exciting source for AE tomography.Secondly, A 6-step description of the SART algorithm is provided and the three dimensional(3D)image contained the damage source locations is visualized by using the proposed algorithm in terms of a locally varying wave velocity distribution. It is shown that the AE tomography based on SART has great potential in the application of structure damage detection. Finally, to further improve the quality of 3D imaging, the Median Filter and the Adaptive Median Filter are used to reduce the noises resulting from AE tomography. The experiment results indicate that Median Filter is the optimal method to remove Salt & Pepper noises.

  19. 40 CFR Table 2d to Subpart Zzzz of... - Requirements for Existing Stationary RICE Located at Area Sources of HAP Emissions

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 14 2013-07-01 2013-07-01 false Requirements for Existing Stationary RICE Located at Area Sources of HAP Emissions 2d Table 2d to Subpart ZZZZ of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR...

  20. Historical Thinking in Information Rich Environments: An Exploration of Eighth Grade Students' Actions Locating and Analyzing Digital Historical Sources

    ERIC Educational Resources Information Center

    List, Jonathan S.

    2012-01-01

    This study uses a bounded case to investigate how students engage in historical inquiry using digital historical sources. Drawing on research and theory related to historical thinking, digital history and new literacies, this study explores how students located historical documents in an online archive and then analyzed those documents given…

  1. Wave-equation Based Earthquake Location

    NASA Astrophysics Data System (ADS)

    Tong, P.; Yang, D.; Yang, X.; Chen, J.; Harris, J.

    2014-12-01

    Precisely locating earthquakes is fundamentally important for studying earthquake physics, fault orientations and Earth's deformation. In industry, accurately determining hypocenters of microseismic events triggered in the course of a hydraulic fracturing treatment can help improve the production of oil and gas from unconventional reservoirs. We develop a novel earthquake location method based on solving full wave equations to accurately locate earthquakes (including microseismic earthquakes) in complex and heterogeneous structures. Traveltime residuals or differential traveltime measurements with the waveform cross-correlation technique are iteratively inverted to obtain the locations of earthquakes. The inversion process involves the computation of the Fréchet derivative with respect to the source (earthquake) location via the interaction between a forward wavefield emitting from the source to the receiver and an adjoint wavefield reversely propagating from the receiver to the source. When there is a source perturbation, the Fréchet derivative not only measures the influence of source location but also the effects of heterogeneity, anisotropy and attenuation of the subsurface structure on the arrival of seismic wave at the receiver. This is essential for the accuracy of earthquake location in complex media. In addition, to reduce the computational cost, we can first assume that seismic wave only propagates in a vertical plane passing through the source and the receiver. The forward wavefield, adjoint wavefield and Fréchet derivative with respect to the source location are all computed in a 2D vertical plane. By transferring the Fréchet derivative along the horizontal direction of the 2D plane into the ones along Latitude and Longitude coordinates or local 3D Cartesian coordinates, the source location can be updated in a 3D geometry. The earthquake location obtained with this combined 2D-3D approach can then be used as the initial location for a true 3D wave

  2. Atomic physics measurements using an ECR ion source located on a 350-kV high-voltage platform

    SciTech Connect

    Dunford, R.W.; Berry, H.G.; Liu, C.J.; Hass, M.; Pardo, R.C.; Raphaelian, M.L.A.; Zabransky, B.J.

    1988-01-01

    We report on a new atomic physics facility at the Argonne PII ECR ion source which was built for the Uranium Upgrade of the ATLAS heavy-ion accelerator. An important feature of our ECR ion source is that it is on a high-voltage platform which provides beam energies of up to 350q keV, where q is the charge of the ion. We discuss the experimental program in progress at this ion source which includes measurements of state-selective electron capture cross sections, photon and electron spectroscopy, studies of quasi-molecular collisions, and polarization studies using an optically pumped Na target. 9 refs., 6 figs.

  3. Contribution of a 3D velocity model and of beam forming method for the location of microseismic sources generated in soft rock landslides

    NASA Astrophysics Data System (ADS)

    Provost, Floriane; Malet, Jean-Philippe; Helmstetter, Agnès; Doubre, Cécile; Gance, Julien

    2016-04-01

    Microseismicity monitoring has proven to be an important tool for a better understanding of the deformation occurring in slow-sliding landslides. However locating the seismic sources generated by a landslide remains a challenging problem due to (1) the small sizes of the landslide, (b) the heterogenous and time-changing petro-physical properties of the landslide material, (c) the complexity of the recorded signals with unclear discriminations of the wave onsets, and (d) the difficulties to install and maintain a dense seismological network on-site close to the seismic sources. We studied the seismic sources generated by the deformation of the clay-rich Super-Sauze landslide (South French Alps). Previous studies show that the most active zone is the uphill part of the landslide within a zone of 300x300m2. Two seismic antennas have been installed on the sides of this zone and a seismic campaign was conducted to build a 3D velocity model of the area. Calibration shots were performed to test the performance of the location method. We show that the use of a 3D velocity model integrated in a beam forming location method slightly improves the accuracy of the shot location epicenter. However, this approach does not help to interpret with confidence the location of the natural events because the horizontal error remains larger than 50m for more than 50% of the shots. Nevertheless, adding station corrections and constraining the grid search area with additional informations based on the signal and the landslide behavior such as SNR, seismic event typology, and surface kinematics of the landslide allow obtaining reliable results. More than 70% of the calibration shots could be located with a horizontal error of less than 40m. The lack of sensor installed in depth as well as the the lack of calibration shots realized at different depths does not permit us to identify the depth of the sources.

  4. Fault location and source process of the Boumerdes, Algeria, earthquake inferred from geodetic and strong motion data

    NASA Astrophysics Data System (ADS)

    Semmane, Fethi; Campillo, Michel; Cotton, Fabrice

    2005-01-01

    The Boumerdes earthquake occurred on a fault whose precise location, offshore the Algerian coast, was unknown. Geodetic data are used to determine the absolute position of the fault. The fault might emerge at about 15 km offshore. Accelerograms are used to infer the space-time history of the rupture using a two-step inversion in the spectral domain. The observed strong motion records agree with the synthetics for the fault location inferred from geodetic data. The fault plane ruptured for about 18 seconds. The slip distribution on the fault indicates one asperity northwest of the hypocenter with maximum slip amplitude about 3 m. This asperity is probably responsible for most of the damage. Another asperity with slightly smaller slip amplitude is located southeast of the hypocenter. The rupture stops its westward propagation close to the Thenia fault, a structure almost perpendicular to the main fault.

  5. PM₁₀ and PM₂.₅ sources at an insular location in the western Mediterranean by using source apportionment techniques.

    PubMed

    Pey, Jorge; Alastuey, Andrés; Querol, Xavier

    2013-07-01

    PM₁₀ and PM₂.₅ chemical composition has been determined at a suburban insular site in the Balearic Islands (Spain) during almost one and a half year. As a result, 200 samples with more than 50 chemical parameters analyzed have been obtained. The whole database has been analyzed by two receptor modelling techniques (Principal Component Analysis and Positive Matrix Factorisation) in order to identify the main PM sources. After that, regression analyses with respect to the PM mass concentrations were conducted to quantify the daily contributions of each source. Four common sources were identified by both receptor models: secondary nitrate coupled with vehicular emissions, secondary sulphate influenced by fuel-oil combustion, aged marine aerosols and mineral dust. In addition, PCA isolated harbour emissions and a mixed anthropogenic factor containing industrial emissions; whereas PMF isolated an additional mineral factor interpreted as road dust+harbour emissions, and a vehicular abrasion products factor. The use of both methodologies appeared complementary. Nevertheless, PMF sources by themselves were better differentiated. Besides these receptor models, a specific methodology to quantify African dust was also applied. The combination of these three source apportionment tools allowed the identification of 8 sources, being 4 of them mineral (African, regional, urban and harbour dusts). As a summary, 29% of PM₁₀ was attributed to natural sources (African dust, regional dust and sea spray), whereas the proportion diminished to 11% in PM₂.₅. Furthermore, the secondary sulphate source, which accounted for about 22 and 32% of PM₁₀ and PM₂.₅, is strongly linked to the aged polluted air masses residing over the western Mediterranean in the warm period. PMID:23611951

  6. Study of the precision of the gamma-ray burst source locations obtained with the Ulysses/PVO/CGRO network

    SciTech Connect

    Cline, T.L. ); Hurley, K.C. ); Sommer, M. ); Boer, M.; Niel, M. ); Fishman, G.; Kouveliotou, C.; Meegan, C.; Paciesas, W.S.; Wilson, R.B. ); Laros, J.G.; Klebesadel, R.W. )

    1994-07-01

    The interplanetary gamma-ray burst network of the [ital Ulysses], [ital Compton]-[ital GRO], and [ital Pioneer]-[ital Venus] [ital Orbiter] missions has made source localizations with fractional-arc-minute precision for a number of events, and with auxiliary data, will provide useful annular-segment loci for many more. These studies have, thus far, yielded one possible counterpart, a [ital Rosat] x-ray association with the 92 May 1 burst. Similar to the historic 1978 November 19 burst/[ital Einstein] association, this possibility gives hope that network studies will provide a fundamental source clue for classical' bursts, just as a second supernova remnant in a network-defined source field has done for sgr events.

  7. Fault location and source process of the 2003 Boumerdes, Algeria, earthquake inferred from geodetic and strong motion data.

    NASA Astrophysics Data System (ADS)

    Semmane, F.; Campillo, M.; Cotton, F.

    2004-12-01

    The Boumerdes earthquake occurred on a fault which precise location, offshore the algerian coast, was unknown. Geodetic data consist of GPS measurements, levelling points and coastal uplifts. They are first used to determine the absolute position of the fault. We performed a series of inversions assuming different positions and chose the model giving the smallest misfit. According to this analysis, the fault emerge at about 15 km offshore. Accelerograms are then used to infer the space-time history of rupture on the fault plane using a two-step inversion in the spectral domain. The observed strong motion records are in good agreement with the synthetics for the fault location inferred from geodetic data. The fault plane ruptured for about 16 seconds. The slip distribution on the fault indicates one asperity north-west of the hypocenter with a maximum slip amplitude larger than 2.5 m. Another asperity with slightly smaller slip amplitude is located south-east of the hypocenter. The rupture seems to stop its propagation westward when it encounters the Thenia fault, a structure almost perpendicular to the main fault. We computed the spatial distribution of ground motion predicted by this fault model and compared it with the observed damages.

  8. Relating landscape characteristics to non-point source pollution in mine waste-located watersheds using geospatial techniques.

    PubMed

    Xiao, Huaguo; Ji, Wei

    2007-01-01

    Landscape characteristics of a watershed are important variables that influence surface water quality. Understanding the relationship between these variables and surface water quality is critical in predicting pollution potential and developing watershed management practices to eliminate or reduce pollution risk. To understand the impacts of landscape characteristics on water quality in mine waste-located watersheds, we conducted a case study in the Tri-State Mining District which is located in the conjunction of three states (Missouri, Kansas and Oklahoma). Severe heavy metal pollution exists in that area resulting from historical mining activities. We characterized land use/land cover over the last three decades by classifying historical multi-temporal Landsat imagery. Landscape metrics such as proportion, edge density and contagion were calculated based on the classified imagery. In-stream water quality data over three decades were collected, including lead, zinc, iron, cadmium, aluminum and conductivity which were used as key water quality indicators. Statistical analyses were performed to quantify the relationship between landscape metrics and surface water quality. Results showed that landscape characteristics in mine waste-located watersheds could account for as much as 77% of the variation of water quality indicators. A single landscape metric alone, such as proportion of mine waste area, could be used to predict surface water quality; but its predicting power is limited, usually accounting for less than 60% of the variance of water quality indicators. PMID:16551489

  9. A Basic Positron Emission Tomography System Constructed to Locate a Radioactive Source in a Bi-dimensional Space.

    PubMed

    Montaño-Zetina, Luis Manuel; Villalobos-Mora, Omar

    2016-01-01

    A simple Positron Emission Tomography (PET) prototype has been constructed to fully characterize its basic working principles. The PET prototype was created by coupling plastic scintillator crystals to photomultipliers or PMT's which are placed at opposing positions to detect two gamma rays emitted from a radioactive source, of which is placed in the geometric center of the PET set-up. The prototype consists of four detectors placed geometrically in a 20 cm diameter circle, and a radioactive source in the center. By moving the radioactive source centimeters from the center the system one is able to detect the displacement by measuring the time of flight difference between any two PMT's and, with this information, the system can calculate the virtual position in a graphical interface. In this way, the prototype reproduces the main principles of a PET system. It is capable to determine the real position of the source with intervals of 4 cm in 2 lines of detection taking less than 2 min. PMID:26863081

  10. Photochemical oxidation and dispersion of gaseous sulfur compounds from natural and anthropogenic sources around a coastal location

    NASA Astrophysics Data System (ADS)

    Song, Sang-Keun; Shon, Zang-Ho; Kim, Ki-Hyun

    The photochemical oxidation and dispersion of reduced sulfur compounds (RSCs: H 2S, CH 3SH, DMS, CS 2, and DMDS) emitted from anthropogenic (A) and natural (N) sources were evaluated based on a numerical modeling approach. The anthropogenic emission concentrations of RSCs were measured from several sampling sites at the Donghae landfill (D-LF) (i.e., source type A) in South Korea during a series of field campaigns (May through December 2004). The emissions of natural RSCs in a coastal study area near the D-LF (i.e., source type N) were estimated from sea surface DMS concentrations and transfer velocity during the same study period. These emission data were then used as input to the CALPUFF dispersion model, revised with 34 chemical reactions for RSCs. A significant fraction of sulfur dioxide (SO 2) was produced photochemically during the summer (about 34% of total SO 2 concentrations) followed by fall (21%), spring (15%), and winter (5%). Photochemical production of SO 2 was dominated by H 2S (about 55% of total contributions) and DMS (24%). The largest impact of RSCs from source type A on SO 2 concentrations occurred around the D-LF during summer. The total SO 2 concentrations produced from source type N around the D-LF during the summer (a mean SO 2 concentration of 7.4 ppbv) were significantly higher than those (≤0.3 ppbv) during the other seasons. This may be because of the high RSC and SO 2 emissions and their photochemistry along with the wind convergence.

  11. Particle sized-resolved source apportionment of primary and secondary organic tracer compounds at urban and rural locations in Spain

    NASA Astrophysics Data System (ADS)

    van Drooge, B. L.; Grimalt, J. O.

    2015-04-01

    Atmospheric particulate matter (PM) was fractionated in six aerodynamic sizes, > 7.2, 7.2-3, 3-1.5, 1.5-1, 1-0.5, < 0.5 μm, using a cascade impactor. These fractions were collected at urban and rural sites during warm and cold seasons. Analysis of the organic tracer compounds by gas-chromatography coupled to mass-spectrometry showed that the composition in the smallest size fractions (< 0.5 μm) was more uniform than in the larger sizes (7.2 > PM > 0.5 μm). Thus, markers of photochemically synthesized organic compounds or combustion sources, either biomass burning or traffic emissions, were predominantly observed in the fraction < 0.5 μm whereas the larger particles were composed of mixed sources from combustion processes, vegetation emissions, soil re-suspension, road dust, urban life-style activities and photochemically synthesized organic compounds. Important seasonal differences were observed at the rural site. In the < 0.5 μm fraction these were related to strong predominance of biomass burning in the cold period and photochemically transformed biogenic organic compounds in the warm period. In the 7.2 > PM > 0.5 μm fractions the differences involved predominant soil-sourced compounds in the warm period and mixed combustion sources, photochemical products and vegetation emissions in the cold. Multivariate Curve Resolution Alternating Least Squares showed that these organic aerosols essentially originated from six source components. Four of them reflected primary emissions related with either natural products, e.g. vegetation emissions and up whirled soil dust, or anthropogenic contributions, e.g. combustion products and compounds related with urban life-style activities, mainly vehicular exhausts and tobacco smoking. Two secondary organic aerosol components were identified. They accumulated in the smallest (< 0.5 μm) or in the larger fractions (> 0.5 μm) and involved strong or mild photochemical transformations of vegetation precursor molecules

  12. Particle size-resolved source apportionment of primary and secondary organic tracer compounds at urban and rural locations in Spain

    NASA Astrophysics Data System (ADS)

    van Drooge, B. L.; Grimalt, J. O.

    2015-07-01

    Atmospheric particulate matter (PM) was fractionated in six aerodynamic sizes, > 7.2, 7.2-3, 3-1.5, 1.5-1, 1-0.5 and < 0.5 μm, using a cascade impactor. These fractions were collected at urban and rural sites during warm and cold seasons. Organic tracer compounds, such as levoglucosan, isoprene, pinene oxidation products, polycyclic aromatic hydrocarbons and quinones, were analyzed by gas chromatography coupled with mass spectrometry. These analyses showed that the composition in the smallest size fractions (< 0.5 μm) was more uniform than in the larger sizes (7.2> PM > 0.5 μm). Thus, markers of photochemically synthesized organic compounds or combustion sources, either biomass burning or traffic emissions, were predominantly observed in the fraction < 0.5 μm, whereas the larger particles were composed of mixed sources from combustion processes, vegetation emissions, soil resuspension, road dust, urban lifestyle activities and photochemically synthesized organic compounds. Important seasonal differences were observed at the rural site. In the < 0.5 μm fraction these were related to a strong predominance of biomass burning in the cold period and photochemically transformed biogenic organic compounds in the warm period. In the 7.2 > PM > 0.5 μm fractions the differences involved predominantly soil-sourced compounds in the warm period and mixed combustion sources, photochemical products and vegetation emissions in the cold. Multivariate curve resolution/alternating least squares showed that these organic aerosols essentially originated from six source components. Four of them reflected primary emissions related to either natural products, e.g., vegetation emissions and upwhirled soil dust, or anthropogenic contributions, e.g., combustion products and compounds related to urban lifestyle activities like vehicular exhaust and tobacco smoking. Two secondary organic aerosol components were identified. They accumulated in the smallest (< 0.5 μm) or in the larger

  13. Brominated flame retardants and polychlorinated biphenyls in human breast milk from several locations in India: potential contaminant sources in a municipal dumping site.

    PubMed

    Devanathan, Gnanasekaran; Subramanian, Annamalai; Sudaryanto, Agus; Takahashi, Shin; Isobe, Tomohiko; Tanabe, Shinsuke

    2012-02-01

    This study investigated the status of contamination of organohalogen compounds (OCs) such as polychlorinated biphenyls (PCBs) and brominated flame retardant (BFRs), including polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) in human milk samples from several locations in India. The levels of OCs were significantly higher in the milk of mothers living in and near municipal dumping site than other locations indicating that the open dumping sites for municipal wastes act as potential sources of these contaminants in India. The PCB concentrations observed in this study tended to decrease compared to those in the matched locations reported previously, probably due to the restriction of technical PCB usage in India. PBDE levels in human milk were two to three folds lower than those of PCBs in all the sampling locations investigated. Congener profiles of PCBs and PBDEs were different between samples from the dumping site mothers and general populations in other areas suggesting the presence of region-specific sources and pathways. HBCDs were detected in human milk from only two sites, with much lower concentrations and detection frequencies compared to PCBs and PBDEs. When hazard quotients (HQs) of PCBs and PBDEs were estimated for infant health risk, the HQs in some milk samples from the dumping site exceeded the threshold value (HQ>1) of PCBs, indicating the potential risk for infants in the specific site. PMID:22208746

  14. Controls of tectonics and sediment source locations on along-strike variations in transgressive deposits on the northern California margin

    USGS Publications Warehouse

    Spinelli, G.A.; Field, M.E.

    2003-01-01

    We identify two surfaces in the shallow subsurface on the Eel River margin offshore northern California, a lowstand erosion surface, likely formed during the last glacial maximum, and an overlying surface likely formed during the most recent transgression of the shoreline. The lowstand erosion surface, which extends from the inner shelf to near the shelfbreak and from the Eel River to Trinidad Head (???80 km), truncates underlying strata on the shelf. Above the surface, inferred transgressive coastal and estuarine sedimentary units separate it from the transgressive surface on the shelf. Early in the transgression, Eel River sediment was likely both transported down the Eel Canyon and dispersed on the slope, allowing transgressive coastal sediment from the smaller Mad River to accumulate in a recognizable deposit on the shelf. The location of coastal Mad River sediment accumulation was controlled by the location of the paleo-Mad River. Throughout the remainder of the transgression, dispersed sediment from the Eel River accumulated an average of 20 m of onlapping shelf deposits. The distribution and thickness of these transgressive marine units was strongly modified by northwest-southeast trending folds. Thick sediment packages accumulated over structural lows in the lowstand surface. The thinnest sediment accumulations (0-10 m) were deposited over structural highs along faults and uplifting anticlines. The Eel margin, an active margin with steep, high sediment-load streams, has developed a thick transgressive systems tract. On this margin sediment accumulates as rapidly as the processes of uplift and downwarp locally create and destroy accommodation space. Sequence stratigraphic models of tectonically active margins should account for variations in accommodation space along margins as well as across them. ?? 2003 Elsevier Science B.V. All rights reserved.

  15. Array analysis methods for detection, classification and location of seismic sources: a first evaluation for aftershock analysis using dense temporary post-seismic array network

    NASA Astrophysics Data System (ADS)

    Poiata, N.; Satriano, C.; Vilotte, J.; Bernard, P.

    2012-12-01

    Detection, separation, classification and location of distributed non stationary seismic sources in broadband noisy environment is an important problem in seismology, in particular for monitoring the high-level post-seismic activity following large subduction earthquakes, like the off-shore Maule (Mw 8.8, 2010) earthquake in Central Chile. Multiple seismic arrays, and local antenna, distributed over a region allow exploiting frequency selective coherence of the signals that arrive at widely-separated array stations, leading to improved detection, convolution blind source separation, and location of distributed non stationary sources. We present here first results on the investigation of time-frequency adaptive array analysis techniques for detection and location of broadband distributed seismic events recorded by the dense temporary seismic network (International Maule Aftershock Deployment, IMAD) installed for monitoring the high-level seismic activity following the 27 February 2010 Maule earthquake (Mw 8.8). This seismic network is characterized by a large aperture, with variable inter-station distances, corroborated with a high level of distributed near and far field seismic source activity and noise. For this study, we first extract from the post-seismic network a number of seismic arrays distributed over the region covered by this network. A first aspect is devoted to passive distributed seismic sources detection, classification and separation. We investigate a number of narrow and wide band signal analysis methods both in time and time-frequency domains for energy arrival detection and tracking, including time adaptive higher order statistics, e.g. like kurtosis, and multiband band-pass filtering, together with adaptive time-frequency transformation and extraction techniques. We demonstrate that these techniques provide superior resolution and robustness than classical STA/LTA techniques in particular in the case of distributed sources with potential signal

  16. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  17. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  18. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  19. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  20. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  1. Argon Cluster Sputtering Source for ToF-SIMS Depth Profiling of Insulating Materials: High Sputter Rate and Accurate Interfacial Information

    SciTech Connect

    Wang, Zhaoying; Liu, Bingwen; Zhao, Evan; Jin, Ke; Du, Yingge; Neeway, James J.; Ryan, Joseph V.; Hu, Dehong; Zhang, Hongliang; Hong, Mina; Le Guernic, Solenne; Thevuthasan, Suntharampillai; Wang, Fuyi; Zhu, Zihua

    2015-08-01

    For the first time, the use of an argon cluster ion sputtering source has been demonstrated to perform superiorly relative to traditional oxygen and cesium ion sputtering sources for ToF-SIMS depth profiling of insulating materials. The superior performance has been attributed to effective alleviation of surface charging. A simulated nuclear waste glass, SON68, and layered hole-perovskite oxide thin films were selected as model systems due to their fundamental and practical significance. Our study shows that if the size of analysis areas is same, the highest sputter rate of argon cluster sputtering can be 2-3 times faster than the highest sputter rates of oxygen or cesium sputtering. More importantly, high quality data and high sputter rates can be achieved simultaneously for argon cluster sputtering while this is not the case for cesium and oxygen sputtering. Therefore, for deep depth profiling of insulating samples, the measurement efficiency of argon cluster sputtering can be about 6-15 times better than traditional cesium and oxygen sputtering. Moreover, for a SrTiO3/SrCrO3 bi-layer thin film on a SrTiO3 substrate, the true 18O/16O isotopic distribution at the interface is better revealed when using the argon cluster sputtering source. Therefore, the implementation of an argon cluster sputtering source can significantly improve the measurement efficiency of insulating materials, and thus can expand the application of ToF-SIMS to the study of glass corrosion, perovskite oxide thin films, and many other potential systems.

  2. The May 29 2008 earthquake aftershock sequence within the South Iceland Seismic Zone: Fault locations and source parameters of aftershocks

    NASA Astrophysics Data System (ADS)

    Brandsdottir, B.; Parsons, M.; White, R. S.; Gudmundsson, O.; Drew, J.

    2010-12-01

    The mid-Atlantic plate boundary breaks up into a series of segments across Iceland. The South Iceland Seismic Zone (SISZ) is a complex transform zone where left-lateral E-W shear between the Reykjanes Peninsula Rift Zone and the Eastern Volcanic Zone is accommodated by bookshelf faulting along N-S lateral strike-slip faults. The SISZ is also a transient feature, migrating sideways in response to the southward propagation of the Eastern Volcanic Zone. Sequences of large earthquakes (M > 6) lasting from days to years and affecting most of the seismic zone have occurred repeatedly in historical time (last 1100 years), separated by intervals of relative quiescence lasting decades to more than a century. On May 29 2008, a Mw 6.1 earthquake struck the western part of the South Iceland Seismic Zone, followed within seconds by a slightly smaller event on a second fault ~5 km further west. Aftershocks, detected by a temporal array of 11 seismometers and three permanent Icelandic Meteorological Office stations were located using an automated Coalescence Microseismic Mapping technique. The epicenters delineate two major and several smaller N-S faults as well as an E-W zone of activity stretching further west into the Reykjanes Peninsula Rift Zone. Fault plane solutions show both right lateral and oblique strike slip mechanisms along the two major N-S faults. The aftershocks deepen from 3-5 km in the north to 8-9 km in the south, suggesting that the main faults dip southwards. The faulting is interpreted to be driven by the local stress due to transform motion between two parallel segments of the divergent plate boundary crossing Iceland.

  3. Mitigation of nonpoint source pesticide contamination in a artificial wetland located at the outlet of a vineyard catchment

    NASA Astrophysics Data System (ADS)

    Payraudeau, S.; Gregoire, C.; Imfeld, G.

    2009-04-01

    The use of artificial wetlands for mitigating nonpoint source pesticide contamination from surface water runoff of agricultural origin represents an innovative approach, whose potential should be evaluated. The EU LIFE project ArtWET assesses the application of ecological bioengineering methods based on various types of artificial wetlands throughout Europe. In this framework, this study focused on the mitigation of pesticides in a storm basin (320 m2; 1500m3; planted with Phragmites australis Cav.) collecting runoff from a vineyard catchment area (42 ha; Rouffach, Alsace, France) over the cultural period (March to October 2008), and whose the hydraulic design has been modified in order to enhance the mitigation process. Discharge measurements and water samples collections were carried out in parallel at the inflow and the outflow of the basin for 17 runoff events in order to evaluate the load of 17 pesticides. Among the target pesticides, Glyphosate, AMPA, its metabolites, and Diuron predominated and runoff event pesticides loads strongly varied throughout cultural period. The depletion of the Glyphosate and AMPA concentration values recorded over the runoff event between the inflow and outflow of the system exceeded 70 %, and reached 90% when considering the total loads over the runoff event. The high mitigation capacity observed in the storm water wetland was likely due to both degradation and sorption processes. Current efforts focus on characterizing the variability over the cropping season of the wetland system performance in terms of reduction of pesticide loads in relationship with the biogeochemical conditions within the storm basin.

  4. Fast and accurate Monte Carlo modeling of a kilovoltage X-ray therapy unit using a photon-source approximation for treatment planning in complex media

    PubMed Central

    Zeinali-Rafsanjani, B.; Mosleh-Shirazi, M. A.; Faghihi, R.; Karbasi, S.; Mosalaei, A.

    2015-01-01

    To accurately recompute dose distributions in chest-wall radiotherapy with 120 kVp kilovoltage X-rays, an MCNP4C Monte Carlo model is presented using a fast method that obviates the need to fully model the tube components. To validate the model, half-value layer (HVL), percentage depth doses (PDDs) and beam profiles were measured. Dose measurements were performed for a more complex situation using thermoluminescence dosimeters (TLDs) placed within a Rando phantom. The measured and computed first and second HVLs were 3.8, 10.3 mm Al and 3.8, 10.6 mm Al, respectively. The differences between measured and calculated PDDs and beam profiles in water were within 2 mm/2% for all data points. In the Rando phantom, differences for majority of data points were within 2%. The proposed model offered an approximately 9500-fold reduced run time compared to the conventional full simulation. The acceptable agreement, based on international criteria, between the simulations and the measurements validates the accuracy of the model for its use in treatment planning and radiobiological modeling studies of superficial therapies including chest-wall irradiation using kilovoltage beam. PMID:26170553

  5. Fast and accurate Monte Carlo modeling of a kilovoltage X-ray therapy unit using a photon-source approximation for treatment planning in complex media.

    PubMed

    Zeinali-Rafsanjani, B; Mosleh-Shirazi, M A; Faghihi, R; Karbasi, S; Mosalaei, A

    2015-01-01

    To accurately recompute dose distributions in chest-wall radiotherapy with 120 kVp kilovoltage X-rays, an MCNP4C Monte Carlo model is presented using a fast method that obviates the need to fully model the tube components. To validate the model, half-value layer (HVL), percentage depth doses (PDDs) and beam profiles were measured. Dose measurements were performed for a more complex situation using thermoluminescence dosimeters (TLDs) placed within a Rando phantom. The measured and computed first and second HVLs were 3.8, 10.3 mm Al and 3.8, 10.6 mm Al, respectively. The differences between measured and calculated PDDs and beam profiles in water were within 2 mm/2% for all data points. In the Rando phantom, differences for majority of data points were within 2%. The proposed model offered an approximately 9500-fold reduced run time compared to the conventional full simulation. The acceptable agreement, based on international criteria, between the simulations and the measurements validates the accuracy of the model for its use in treatment planning and radiobiological modeling studies of superficial therapies including chest-wall irradiation using kilovoltage beam. PMID:26170553

  6. Spatial distribution of source locations for particulate nitrate and sulfate in the upper-midwestern United States

    NASA Astrophysics Data System (ADS)

    Zhao, Weixiang; Hopke, Philip K.; Zhou, Liming

    Two back-trajectory analysis methods designed to be used with multiple site data, simplified quantitative transport bias analysis (SQTBA) and residence time weighted concentration (RTWC), were applied to nitrate and sulfate concentration data from two rural sites (the Mammoth Cave National Park and the Great Smoky Mountain National Park) and five urban sites (Chicago, Cleveland, Detroit, Indianapolis, and St. Louis) for an intensive investigation on the spatial patterns of origins for these two species in the upper-midwestern area. The study was made by dividing the data into five categories: all sites and all seasons, rural sites in summer, rural sites in winter, urban sites in summer, and urban sites in winter. A general conclusion was that the origins of the nitrate in these seven sites were mainly in the upper-midwestern areas, while the sulfate in these seven sites were mainly from the Ohio and Tennessee River Valley areas. The upper-midwestern areas are regions of high ammonia emissions rather than high NO x emissions. In the winter, metropolitan areas showed the highest nitrate emission potential suggesting the importance of local NO x emissions. In the summer, ammonia emissions from fertilizer application in the lower midwestern area made a significant contribution to nitrate in the rural sites of this study. The impact of the wind direction prevalence on the source spatial patterns was observed by comparing the urban and rural patterns of the summer. The differences between the results of two methods are discussed and suggestions for applying these methods are also provided.

  7. An Aneurysmal Left Circumflex Artery-to-Right Atrium Fistula in a Patient with Ischemic Symptoms: Accurate Diagnosis with Dual-Source CT Angiography

    SciTech Connect

    Oncel, Dilek Oncel, Guray

    2008-07-15

    In this report, we present a 55-year-old female patient with a left circumflex artery-to-right atrial fistula associated with a huge saccular aneurysm. She had undergone conventional angiography due to ischemic symptoms. In conventional angiography, a very dilated and tortuous vessel originating from the circumflex artery and continuous with a huge saccular aneurysm was visualized but the drainage site could not be demonstrated. With dual-source CT coronary angiography, the exact anatomy of this fistula was demonstrated and surgery was planned.

  8. Calibration and operational data for a compact photodiode detector useful for monitoring the location of moving sources of positron emitting radioisotopes

    NASA Astrophysics Data System (ADS)

    Marsland, M. G.; Dehnel, M. P.; Johansson, S.; Rajander, J.; Solin, O.; Theroux, J.; Stewart, T. M.; Christensen, T.; Hollinger, C.

    2013-04-01

    D-Pace has developed a compact cost-effective gamma detector system based on technology licensed from TRIUMF [1]. These photodiode detectors are convenient for detecting the presence of positron emitting radioisotopes, particularly for the case of transport of radioisotopes from a PET cyclotron to hotlab, or from one location to another in an automated radiochemistry processing unit. This paper describes recent calibration experiments undertaken at the Turku PET Centre for stationary and moving sources of F18 and C11 in standard setups. The practical diagnostic utility of using several of these devices to track the transport of radioisotopes from the cyclotron to hotlab is illustrated. For example, such a detector system provides: a semi-quantitative indication of total activity, speed of transport, location of any activity lost en route and effectiveness of follow-up system flushes, a means of identifying bolus break-up, feedback useful for deciding when to change out tubing.

  9. Calibration and operational data for a compact photodiode detector useful for monitoring the location of moving sources of positron emitting radioisotopes

    SciTech Connect

    Marsland, M. G.; Dehnel, M. P.; Theroux, J.; Christensen, T.; Hollinger, C.; Johansson, S.; Rajander, J.; Solin, O.; Stewart, T. M.

    2013-04-19

    D-Pace has developed a compact cost-effective gamma detector system based on technology licensed from TRIUMF. These photodiode detectors are convenient for detecting the presence of positron emitting radioisotopes, particularly for the case of transport of radioisotopes from a PET cyclotron to hotlab, or from one location to another in an automated radiochemistry processing unit. This paper describes recent calibration experiments undertaken at the Turku PET Centre for stationary and moving sources of F18 and C11 in standard setups. The practical diagnostic utility of using several of these devices to track the transport of radioisotopes from the cyclotron to hotlab is illustrated. For example, such a detector system provides: a semi-quantitative indication of total activity, speed of transport, location of any activity lost en route and effectiveness of follow-up system flushes, a means of identifying bolus break-up, feedback useful for deciding when to change out tubing.

  10. LLNL Location and Detection Research

    SciTech Connect

    Myers, S C; Harris, D B; Anderson, M L; Walter, W R; Flanagan, M P; Ryall, F

    2003-07-16

    We present two LLNL research projects in the topical areas of location and detection. The first project assesses epicenter accuracy using a multiple-event location algorithm, and the second project employs waveform subspace Correlation to detect and identify events at Fennoscandian mines. Accurately located seismic events are the bases of location calibration. A well-characterized set of calibration events enables new Earth model development, empirical calibration, and validation of models. In a recent study, Bondar et al. (2003) develop network coverage criteria for assessing the accuracy of event locations that are determined using single-event, linearized inversion methods. These criteria are conservative and are meant for application to large bulletins where emphasis is on catalog completeness and any given event location may be improved through detailed analysis or application of advanced algorithms. Relative event location techniques are touted as advancements that may improve absolute location accuracy by (1) ensuring an internally consistent dataset, (2) constraining a subset of events to known locations, and (3) taking advantage of station and event correlation structure. Here we present the preliminary phase of this work in which we use Nevada Test Site (NTS) nuclear explosions, with known locations, to test the effect of travel-time model accuracy on relative location accuracy. Like previous studies, we find that the reference velocity-model and relative-location accuracy are highly correlated. We also find that metrics based on travel-time residual of relocated events are not a reliable for assessing either velocity-model or relative-location accuracy. In the topical area of detection, we develop specialized correlation (subspace) detectors for the principal mines surrounding the ARCES station located in the European Arctic. Our objective is to provide efficient screens for explosions occurring in the mines of the Kola Peninsula (Kovdor, Zapolyarny

  11. Application of a Persistent Dissolved-phase Reactive Treatment Zone for Mitigation of Mass Discharge from Sources Located in Lower-Permeability Sediments

    PubMed Central

    Marble, J.C.; Brusseau, M.L.; Carroll, K.C.; Plaschke, M.; Fuhrig, L.; Brinker, F.

    2015-01-01

    The purpose of this study is to examine the development and effectiveness of a persistent dissolved-phase treatment zone, created by injecting potassium permanganate solution, for mitigating discharge of contaminant from a source zone located in a relatively deep, low-permeability formation. A localized 1,1-dichloroethene (DCE) source zone comprising dissolved- and sorbed-phase mass is present in lower permeability strata adjacent to a sand/gravel unit in a section of the Tucson International Airport Area (TIAA) Superfund Site. The results of bench-scale studies conducted using core material collected from boreholes drilled at the site indicated that natural oxidant demand was low, which would promote permanganate persistence. The reactive zone was created by injecting a permanganate solution into multiple wells screened across the interface between the lower-permeability and higher-permeability units. The site has been monitored for nine years to characterize the spatial distribution of DCE and permanganate. Permanganate continues to persist at the site, and a substantial and sustained decrease in DCE concentrations in groundwater has occurred after the permanganate injection.. These results demonstrate successful creation of a long-term, dissolved-phase reactive-treatment zone that reduced mass discharge from the source. This project illustrates the application of in-situ chemical oxidation as a persistent dissolved-phase reactive-treatment system for lower-permeability source zones, which appears to effectively mitigate persistent mass discharge into groundwater. PMID:26300570

  12. Locating Desired Source Rocks by Using Shallow Ground Penetrating Radar and Seismic Survey Methods in western Washington, Pacific Northwest of the U.S

    NASA Astrophysics Data System (ADS)

    Cakir, R.; Meng, X.; Butler, Q.; Jenkins, J.; Keck, J.; Walsh, T. J.

    2015-12-01

    The Washington State Department of Natural Resources (WADNR) manages 2.1 million acres of forested state trust lands in Washington. WADNR sells timber and other agricultural products to help fund local services and the construction of institutions such as public schools and universities. Quality of rocks used as a surface on the roads built to access the timber is the essential and selecting appropriate rock quarry locations is challenging. Traditional borehole drilling methods only provide information from discrete locations. The study was conducted in the Capitol Forest area of western Washington. In our previous study, we suggested that a combination of P-wave seismic and ground penetrating radar (GPR) can be a rapid, comprehensive and cost effective alternative for identifying desired rock sources. In this study, we further improved upon that method and accomplished the following: 1) rock quality at a relatively fine resolution was distinguished and 2) the spatial variability of the rock was identified. Both 450 MHz and 80 MHz GPR antennas were used to obtain high resolution radargrams in the near-surface zone with 5m maximum penetration depth and lower resolution radargrams in the deeper subsurface zone with about 20m maximum penetration depth. We then correlated the GPR radargrams with P-wave velocities using the refraction survey data as well as S-wave velocities, estimated using Multi-Channel Analysis of Surface Waves (MASW) survey data. Additionally, nearby test pits and boreholes (maximum depth = 15 meters) were used to confirm the geophysical measurements. Our study results demonstrate that the combination of GPR, using the two antennas, and seismic surveys provides very useful subsurface information regarding quality and spatial distribution of the rocks beneath the overburden. Subsurface images gathered from these combined geophysical methods do assist quarry operators to rapidly locate the desired rock sources.

  13. Locating radiation hazards and sources within contaminated areas by implementing a reverse ray tracing technique in the RadBall™ technology.

    PubMed

    Farfán, Eduardo B; Stanley, Steven; Holmes, Christopher; Lennox, Kathryn; Oldham, Mark; Clift, Corey; Thomas, Andrew; Adamovics, John

    2012-02-01

    RadBall™ is a novel technology that can locate unknown radioactive hazards within contaminated areas, hot cells, and gloveboxes. The device consists of a colander-like outer tungsten collimator that houses a radiation-sensitive polymer semisphere. The collimator has a number of small holes; as a result, specific areas of the polymer are exposed to radiation, becoming increasingly more opaque in proportion to the absorbed dose. The polymer semisphere is imaged in an optical computed tomography scanner that produces a high resolution three-dimensional map of optical attenuation coefficients. A subsequent analysis of the optical attenuation data, using a reverse ray tracing technique, provides information on the spatial distribution of gamma-ray sources in a given area, forming a three-dimensional characterization of the area of interest. The RadBall™ technology and its reverse ray tracing technique were investigated using known radiation sources at the Savannah River Site's Health Physics Instrument Calibration Laboratory and unknown sources at the Savannah River National Laboratory's Shielded Cells facility. PMID:22217592

  14. Acoustic Location of Lightning Using Interferometric Techniques

    NASA Astrophysics Data System (ADS)

    Erives, H.; Arechiga, R. O.; Stock, M.; Lapierre, J. L.; Edens, H. E.; Stringer, A.; Rison, W.; Thomas, R. J.

    2013-12-01

    Acoustic arrays have been used to accurately locate thunder sources in lightning flashes. The acoustic arrays located around the Magdalena mountains of central New Mexico produce locations which compare quite well with source locations provided by the New Mexico Tech Lightning Mapping Array. These arrays utilize 3 outer microphones surrounding a 4th microphone located at the center, The location is computed by band-passing the signal to remove noise, and then computing the cross correlating the outer 3 microphones with respect the center reference microphone. While this method works very well, it works best on signals with high signal to noise ratios; weaker signals are not as well located. Therefore, methods are being explored to improve the location accuracy and detection efficiency of the acoustic location systems. The signal received by acoustic arrays is strikingly similar to th signal received by radio frequency interferometers. Both acoustic location systems and radio frequency interferometers make coherent measurements of a signal arriving at a number of closely spaced antennas. And both acoustic and interferometric systems then correlate these signals between pairs of receivers to determine the direction to the source of the received signal. The primary difference between the two systems is the velocity of propagation of the emission, which is much slower for sound. Therefore, the same frequency based techniques that have been used quite successfully with radio interferometers should be applicable to acoustic based measurements as well. The results presented here are comparisons between the location results obtained with current cross correlation method and techniques developed for radio frequency interferometers applied to acoustic signals. The data were obtained during the summer 2013 storm season using multiple arrays sensitive to both infrasonic frequency and audio frequency acoustic emissions from lightning. Preliminary results show that

  15. The Use of LiDAR Elevation Data and Satellite Imagery to Locate Critical Source Areas to Diffuse Pollution in Agricultural Watersheds

    NASA Astrophysics Data System (ADS)

    Drouin, Ariane; Michaud, Aubert; Thériault, Georges; Beaudin, Isabelle; Rodrigue, Jean-François; Denault, Jean-Thomas; Desjardins, Jacques; Côté, Noémi

    2013-04-01

    In Quebec / Canada, water quality improvement in rural areas greatly depends on the reduction of diffuse pollution. Indeed, point source pollution has been reduced significantly in Canada in recent years by creating circumscribed pits for manure and removing animals from stream. Diffuse pollution differs from point source pollution because it is spread over large areas. In agricultural areas, sediment loss by soil and riverbank erosion along with loss of nutrients (phosphorus, nitrogen, etc.) and pesticides from fields represent the main source of non-point source pollution. The factor mainly responsible for diffuse pollution in agricultural areas is surface runoff occurring in poorly drained areas in fields. The presence of these poorly drained areas is also one of the most limiting factors in crop productivity. Thus, a reconciliation of objectives at the farm (financial concern for farmers) and off-farm concerns (environmental concern) is possible. In short, drainage, runoff, erosion, water quality and crop production are all interconnected issues that need to be tackled together. Two complementary data sources are mainly used in the diagnosis of drainage, surface runoff and erosion : elevation data and multispectral satellite images. In this study of two watersheds located in Québec (Canada), LiDAR elevation data and satellite imagery (QuickBird, Spot and Landsat) were acquired. The studied territories have been partitioned in hydrologic response units (HRUs) according to sub-basins, soils, elevation (topographic index) and land use. These HRUs are afterwards used in a P index software (P-Edit) that calculates the quantities of sediments and phosphorus exported from each HRUs. These exports of sediments and phosphorus are validated with hydrometric and water quality data obtain in two sub-basins and are also compared to soil brightness index derived from multispectral images. This index is sensitive to soil moisture and thus highlights areas where the soil is

  16. Data on milk dioxin contamination linked with the location of fodder croplands allow to hypothesize the origin of the pollution source in an Italian valley.

    PubMed

    Desiato, Rosanna; Bertolini, Silvia; Baioni, Elisa; Crescio, Maria Ines; Scortichini, Giampiero; Ubaldi, Alessandro; Sparagna, Bruno; Cuttica, Giancarlo; Ru, Giuseppe

    2014-11-15

    Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) have similar toxic, endocrine-disrupting, and carcinogenic activity. They are classified as persistent organic pollutants accumulating in the environment and the tissues of living organisms. High concentrations of PCDD/F and dl-PCB have been detected in bovine milk collected in a Piedmont valley (Northwestern Italy) since 2004. This geographic study describes the local distribution of pollution from PCDD/Fs and dl-PCBs. Since their presence in animal products could be traced back to the ingestion of contaminated fodder, dioxin levels in cow milk were related to the distribution of fodder cropland parcels. Specifically, the aim of the study was to determine, through an exploratory approach, whether the contamination was consistent with one common point source of contamination or different scattered sources. Data for PCDD/F and dl-PCB concentrations in the bulk milk from 27 herds, sampled over a 4-year period (2004-2007), were matched to the georeferenced land parcels the dairy farmers used for growing fodder. Isopleth maps of dioxin concentrations were estimated with ordinary kriging. The highest level of pollution for both PCDD/Fs and dl-PCBs was geographically juxtaposed: in both instances, the location of the local steel plant was within this extremely highly polluted area. The study results support the hypothesis for one common point source of contamination in the valley. The exploratory spatial analysis applied in this research may provide a valuable, novel approach to straightforward identification of a highly likely source of dioxin contamination of dairy products (even in the absence of top soil contamination data). PMID:25194902

  17. Laser measuring system accurately locates point coordinates on photograph

    NASA Technical Reports Server (NTRS)

    Doede, J. H.; Lindenmeyer, C. W.; Vonderohe, R. H.

    1966-01-01

    Laser activated ultraprecision ranging apparatus interfaced with a computer determines point coordinates on a photograph. A helium-neon gas CW laser provides collimated light for a null balancing optical system. This system has no mechanical connection between the ranging apparatus and the photograph.

  18. Cable-fault locator

    NASA Technical Reports Server (NTRS)

    Cason, R. L.; Mcstay, J. J.; Heymann, A. P., Sr.

    1979-01-01

    Inexpensive system automatically indicates location of short-circuited section of power cable. Monitor does not require that cable be disconnected from its power source or that test signals be applied. Instead, ground-current sensors are installed in manholes or at other selected locations along cable run. When fault occurs, sensors transmit information about fault location to control center. Repair crew can be sent to location and cable can be returned to service with minimum of downtime.

  19. Coupled HBO and NBO Variations in the Z Source GX 5-1: Inner Accretion Disk as the Location of QPOs

    NASA Astrophysics Data System (ADS)

    Sriram, K.; Rao, A. R.; Choi, C. S.

    2011-12-01

    The simultaneous and coupled evolution of horizontal branch oscillation (HBO) and normal branch oscillation (NBO) in Z-type sources suggests that the production of HBO is connected to NBO and is caused by changes in the physical/radiative properties of the inner accretion disk, although there is a lack of substantial spectral evidence to support this. In this Letter, we present the results of an analysis of an RXTE observation of the Z source GX 5-1, where the 6 Hz NBO is simultaneously detected along with an HBO at 51 Hz. The variations in the intensity and the associated power density spectrum indicate that the HBO and NBO are strongly coupled, originating from the same location in the inner accretion disk. The absence of HBO and NBO in the lower energy bands, an increase in the rms amplitude with energy, and a smooth transition among them suggest that they are produced in the hot inner regions of the accretion disk. Based on a spectral analysis, we found a signature of changing or physically modified inner disk front during the coupled HBO and NBO evolution. We explore the various models to explain the observed phenomenon and propose that the NBO is affiliated to the oscillations in the thick/puffed-up inner region of the accretion disk.

  20. COUPLED HBO AND NBO VARIATIONS IN THE Z SOURCE GX 5-1: INNER ACCRETION DISK AS THE LOCATION OF QPOs

    SciTech Connect

    Sriram, K.; Choi, C. S.; Rao, A. R.

    2011-12-20

    The simultaneous and coupled evolution of horizontal branch oscillation (HBO) and normal branch oscillation (NBO) in Z-type sources suggests that the production of HBO is connected to NBO and is caused by changes in the physical/radiative properties of the inner accretion disk, although there is a lack of substantial spectral evidence to support this. In this Letter, we present the results of an analysis of an RXTE observation of the Z source GX 5-1, where the 6 Hz NBO is simultaneously detected along with an HBO at 51 Hz. The variations in the intensity and the associated power density spectrum indicate that the HBO and NBO are strongly coupled, originating from the same location in the inner accretion disk. The absence of HBO and NBO in the lower energy bands, an increase in the rms amplitude with energy, and a smooth transition among them suggest that they are produced in the hot inner regions of the accretion disk. Based on a spectral analysis, we found a signature of changing or physically modified inner disk front during the coupled HBO and NBO evolution. We explore the various models to explain the observed phenomenon and propose that the NBO is affiliated to the oscillations in the thick/puffed-up inner region of the accretion disk.

  1. Characterization and treatment of water used for human consumption from six sources located in the Cameron/Tuba City abandoned uranium mining area.

    PubMed

    Orescanin, Visnja; Kollar, Robert; Nad, Karlo; Mikelic, Ivanka Lovrencic; Kollar, Iris

    2011-01-01

    The purpose of this research was the characterization and improvement of the quality of water used for human consumption of unregulated/regulated water sources located in the Cameron/Tuba City abandoned uranium mining area (NE Arizona, western edge of the Navajo Nation). Samples were collected at six water sources which included regulated sources: Wind Mill (Tank 3T-538), Badger Springs and Paddock Well as well as unregulated sources: Willy Spring, Water Wall and Water Hole. Samples taken from Wind Mill, Water Wall and Water Hole were characterized with high turbidity and color as well as high level of manganese, iron and nickel and elevated value of molybdenum. High level of iron was also found in Badger Spring, Willy Spring, and Paddock Well. These three water sources were also characterized with elevated values of fluoride and vanadium. Significant amounts of zinc were found in Water Wall and Water Hole samples. Water Wall sample was also characterized with high level of Cr(VI). Compared to primary or secondary Navajo Nation Environmental Protection Agency (NNEPA) water quality standard the highest enrichment was found for turbidity (50.000 times), color (up to 1.796 times) and manganese (71 times), Cr(VI) (17.5 times), iron (7.4 times) and arsenic (5.2 times). Activities of (226)Ra and (238)U in water samples were still in agreement with the maximum contaminant levels. In order to comply with NNEPA water quality standard water samples were subjected to electrochemical treatment. This method was selected due to its high removal efficiency for heavy metals and uranium, lower settlement time, production of smaller volume of waste mud and higher stability of waste mud compared to physico-chemical treatment. Following the treatment, concentrations of heavy metals and activities of radionuclides in all samples were significantly lower compared to NNEPA or WHO regulated values. The maximum removal efficiencies for color, turbidity, arsenic, manganese, molybdenum and

  2. Co-located monogenetic eruptions ~200 kyr apart driven by tapping vertically separated mantle source regions, Chagwido, Jeju Island, Republic of Korea

    NASA Astrophysics Data System (ADS)

    Brenna, Marco; Németh, Károly; Cronin, Shane J.; Sohn, Young Kwan; Smith, Ian E. M.; Wijbrans, Jan

    2015-05-01

    -developed paleosol represents at least 200 kyr between the two co-located eruptions. The distinctive magma compositions show that each eruption tapped an independent region within the same underlying mantle source. These observations show that contrary to most assumptions of monogenetic volcanism, an already "tapped" source region may become fertile again through mantle convection/migration and eruptions can thus be expected from old vent sites in long-lived volcanic fields.

  3. Strength Restoration of Cracked Sandstone and Coal under a Uniaxial Compression Test and Correlated Damage Source Location Based on Acoustic Emissions.

    PubMed

    Feng, Xiaowei; Zhang, Nong; Zheng, Xigui; Pan, Dongjiang

    2015-01-01

    Underground rock masses have shown a general trend of natural balance over billions of years of ground movement. Nonetheless, man-made underground constructions disturb this balance and cause rock stability failure. Fractured rock masses are frequently encountered in underground constructions, and this study aims to restore the strength of rock masses that have experienced considerable fracturing under uniaxial compression. Coal and sandstone from a deep-buried coal mine were chosen as experimental subjects; they were crushed by uniaxial compression and then carefully restored by a chemical adhesive called MEYCO 364 with an innovative self-made device. Finally, the restored specimens were crushed once again by uniaxial compression. Axial stress, axial strain, circumferential strain, and volumetric strain data for the entire process were fully captured and are discussed here. An acoustic emission (AE) testing system was adopted to cooperate with the uniaxial compression system to provide better definitions for crack closure thresholds, crack initiation thresholds, crack damage thresholds, and three-dimensional damage source locations in intact and restored specimens. Several remarkable findings were obtained. The restoration effects of coal are considerably better than those of sandstone because the strength recovery coefficient of the former is 1.20, whereas that of the latter is 0.33, which indicates that MEYCO 364 is particularly valid for fractured rocks whose initial intact peak stress is less than that of MEYCO 364. Secondary cracked traces of restored sandstone almost follow the cracked traces of the initial intact sandstone, and the final failure is mainly caused by decoupling between the adhesive and the rock mass. However, cracked traces of restored coal only partially follow the traces of intact coal, with the final failure of the restored coal being caused by both bonding interface decoupling and self-breakage in coal. Three-dimensional damage source

  4. Strength Restoration of Cracked Sandstone and Coal under a Uniaxial Compression Test and Correlated Damage Source Location Based on Acoustic Emissions

    PubMed Central

    Feng, Xiaowei; Zhang, Nong; Zheng, Xigui; Pan, Dongjiang

    2015-01-01

    Underground rock masses have shown a general trend of natural balance over billions of years of ground movement. Nonetheless, man-made underground constructions disturb this balance and cause rock stability failure. Fractured rock masses are frequently encountered in underground constructions, and this study aims to restore the strength of rock masses that have experienced considerable fracturing under uniaxial compression. Coal and sandstone from a deep-buried coal mine were chosen as experimental subjects; they were crushed by uniaxial compression and then carefully restored by a chemical adhesive called MEYCO 364 with an innovative self-made device. Finally, the restored specimens were crushed once again by uniaxial compression. Axial stress, axial strain, circumferential strain, and volumetric strain data for the entire process were fully captured and are discussed here. An acoustic emission (AE) testing system was adopted to cooperate with the uniaxial compression system to provide better definitions for crack closure thresholds, crack initiation thresholds, crack damage thresholds, and three-dimensional damage source locations in intact and restored specimens. Several remarkable findings were obtained. The restoration effects of coal are considerably better than those of sandstone because the strength recovery coefficient of the former is 1.20, whereas that of the latter is 0.33, which indicates that MEYCO 364 is particularly valid for fractured rocks whose initial intact peak stress is less than that of MEYCO 364. Secondary cracked traces of restored sandstone almost follow the cracked traces of the initial intact sandstone, and the final failure is mainly caused by decoupling between the adhesive and the rock mass. However, cracked traces of restored coal only partially follow the traces of intact coal, with the final failure of the restored coal being caused by both bonding interface decoupling and self-breakage in coal. Three-dimensional damage source

  5. Studies of the flickering in cataclysmic variables. VI. The location of the flickering light source in HT Cassiopeiae, V2051 Ophiuchi, IP Pegasi and UX Ursae Majoris

    NASA Astrophysics Data System (ADS)

    Bruch, A.

    2000-07-01

    The scatter in the light curves of four eclipsing cataclysmic variables (CVs) is analyzed in order to find constraints for the location of the flickering light source in these systems. In all cases the ``scatter curves'' contain well defined eclipses which begin and end exactly at the phases of eclipse ingress and egress of individual system components: In HT Cas, V2051 Oph and UX UMa the scatter eclipse coincides with the white dwarf eclipse, in IP Peg with the hot spot eclipse. Moreover, in V2051 Oph, IP Peg and UX UMa the scatter is enhanced during phases of visibility of the hot spot. Together with similar results from earlier investigations these findings leave little doubt that the flickering in CVs can originate in two regions: the innermost accretions disk with the boundary layer and the white dwarf surface, and the region of impact of the stream of transferred matter from the secondary star upon the accretion disk. Two different techniques (termed `single' and `ensemble' method) to measure the scatter curves of CVs are advocated in the literature. A critical comparison of these techniques is performed. It is found that the `ensemble' method yields reasonable results only under specific circumstances.

  6. Super-Sonograms and graphical seismic source locations: Facing the challenge of real-time data processing in an OSI SAMS installation

    NASA Astrophysics Data System (ADS)

    Joswig, Manfred

    2010-05-01

    The installation and operation of an OSI seismic aftershock monitoring system (SAMS) is bound by strict time constraints: 30+ small arrays must be set up within days, and data screening must cope with the daily seismogram input. This is a significant challenge since any potential, single ML -2.0 aftershock from a potential nuclear test must be detected and discriminated against a variety of higher-amplitude noise bursts. No automated approach can handle this task to date; thus some 200 traces of 24/7 data must be screened manually with a time resolution sufficient to recover signals of just a few sec duration, and with tiny amplitudes just above the threshold of ambient noise. Previous tests confirmed that this task can not be performed by time-domain signal screening via established seismological processing software, e.g. PITSA, SEISAN, or GEOTOOLS. Instead, we introduced 'SonoView', a seismic diagnosis tool based on a compilation of array traces into super-sonograms. Several hours of cumulative array data can be displayed at once on a single computer screen - without sacrifying the necessary detectability of few-sec signals. Then 'TraceView' will guide the analyst to select the relevant traces with best SNR, and 'HypoLine' offers some interactive, graphical location tools for fast epicenter estimates and source signature identifications. A previous release of this software suite was successfully applied at IFE08 in Kasakhstan, and supported the seismic sub-team of OSI in its timely report compilation.

  7. Accurate, reliable prototype earth horizon sensor head

    NASA Technical Reports Server (NTRS)

    Schwarz, F.; Cohen, H.

    1973-01-01

    The design and performance is described of an accurate and reliable prototype earth sensor head (ARPESH). The ARPESH employs a detection logic 'locator' concept and horizon sensor mechanization which should lead to high accuracy horizon sensing that is minimally degraded by spatial or temporal variations in sensing attitude from a satellite in orbit around the earth at altitudes in the 500 km environ 1,2. An accuracy of horizon location to within 0.7 km has been predicted, independent of meteorological conditions. This corresponds to an error of 0.015 deg-at 500 km altitude. Laboratory evaluation of the sensor indicates that this accuracy is achieved. First, the basic operating principles of ARPESH are described; next, detailed design and construction data is presented and then performance of the sensor under laboratory conditions in which the sensor is installed in a simulator that permits it to scan over a blackbody source against background representing the earth space interface for various equivalent plant temperatures.

  8. Eldercare Locator

    MedlinePlus

    ... page content Skip Navigation Department of Health and Human Services Your Browser ... Welcome to the Eldercare Locator, a public service of the U.S. Administration on Aging connecting you to services for older ...

  9. Grading More Accurately

    ERIC Educational Resources Information Center

    Rom, Mark Carl

    2011-01-01

    Grades matter. College grading systems, however, are often ad hoc and prone to mistakes. This essay focuses on one factor that contributes to high-quality grading systems: grading accuracy (or "efficiency"). I proceed in several steps. First, I discuss the elements of "efficient" (i.e., accurate) grading. Next, I present analytical results…

  10. Earthquake location in island arcs

    USGS Publications Warehouse

    Engdahl, E.R.; Dewey, J.W.; Fujita, K.

    1982-01-01

    -velocity lithospheric slab. In application, JHD has the practical advantage that it does not require the specification of a theoretical velocity model for the slab. Considering earthquakes within a 260 km long by 60 km wide section of the Aleutian main thrust zone, our results suggest that the theoretical velocity structure of the slab is presently not sufficiently well known that accurate locations can be obtained independently of locally recorded data. Using a locally recorded earthquake as a calibration event, JHD gave excellent results over the entire section of the main thrust zone here studied, without showing a strong effect that might be attributed to spatially varying source-station anomalies. We also calibrated the ray-tracing method using locally recorded data and obtained results generally similar to those obtained by JHD. ?? 1982.

  11. Accurate monotone cubic interpolation

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1991-01-01

    Monotone piecewise cubic interpolants are simple and effective. They are generally third-order accurate, except near strict local extrema where accuracy degenerates to second-order due to the monotonicity constraint. Algorithms for piecewise cubic interpolants, which preserve monotonicity as well as uniform third and fourth-order accuracy are presented. The gain of accuracy is obtained by relaxing the monotonicity constraint in a geometric framework in which the median function plays a crucial role.

  12. Accurate Finite Difference Algorithms

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.

    1996-01-01

    Two families of finite difference algorithms for computational aeroacoustics are presented and compared. All of the algorithms are single step explicit methods, they have the same order of accuracy in both space and time, with examples up to eleventh order, and they have multidimensional extensions. One of the algorithm families has spectral like high resolution. Propagation with high order and high resolution algorithms can produce accurate results after O(10(exp 6)) periods of propagation with eight grid points per wavelength.

  13. Properties of the near-field term and its effect on polarisation analysis and source locations of long-period (LP) and very-long-period (VLP) seismic events at volcanoes

    NASA Astrophysics Data System (ADS)

    Lokmer, Ivan; Bean, Christopher J.

    2010-04-01

    Seismicity that originates within volcanic magmatic and hydrothermal plumbing systems is characterised by wavelengths that are often comparable to or longer than the source-receiver distance. The effect of such a near-field configuration must be explored when analysing these signals. Herein, we summarise properties of near-field observations for both a single force and moment-tensor seismic sources. We show radiation patterns of the near-, intermediate- and far-field terms for the source types that are most likely candidates for long- (LP) and very-long-period (VLP) volcanic seismicity, including: a single force, compensated linear vector dipole (CLVD), a tensile crack and a pipe-like source. We find that the deviation of the first motion polarisation from the radial direction is significant in all planes except one whose normal is parallel to the symmetry axis (if there is one) of the source mechanism. However, this deviation is less pronounced (or even negligible), when there is a considerable volumetric component in the source (as in the case of a tensile crack or pipe). Our location test shows that the accuracy of locations obtained using the semblance or cross-correlation techniques is very significantly affected by the near-field geometry. This effect is especially pronounced for shallow sources, such as often encountered on volcanoes, and decreases with increasing source depth. Hence, in practical applications on volcanoes, 3D full waveform numerical simulation (including topography and structural heterogeneities) should be used in order to both validate location techniques and as an interpretational aid to reduce misinterpretations of location results.

  14. Accurate measurement of time

    NASA Astrophysics Data System (ADS)

    Itano, Wayne M.; Ramsey, Norman F.

    1993-07-01

    The paper discusses current methods for accurate measurements of time by conventional atomic clocks, with particular attention given to the principles of operation of atomic-beam frequency standards, atomic hydrogen masers, and atomic fountain and to the potential use of strings of trapped mercury ions as a time device more stable than conventional atomic clocks. The areas of application of the ultraprecise and ultrastable time-measuring devices that tax the capacity of modern atomic clocks include radio astronomy and tests of relativity. The paper also discusses practical applications of ultraprecise clocks, such as navigation of space vehicles and pinpointing the exact position of ships and other objects on earth using the GPS.

  15. Accurate quantum chemical calculations

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

    1989-01-01

    An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently accurate result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI wave functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform accurate calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.

  16. CT-Analyst: fast and accurate CBR emergency assessment

    NASA Astrophysics Data System (ADS)

    Boris, Jay; Fulton, Jack E., Jr.; Obenschain, Keith; Patnaik, Gopal; Young, Theodore, Jr.

    2004-08-01

    An urban-oriented emergency assessment system for airborne Chemical, Biological, and Radiological (CBR) threats, called CT-Analyst and based on new principles, gives greater accuracy and much greater speed than possible with current alternatives. This paper explains how this has been done. The increased accuracy derives from detailed, three-dimensional CFD computations including, solar heating, buoyancy, complete building geometry specification, trees, wind fluctuations, and particle and droplet distributions (as appropriate). This paper shows how a very finite number of such computations for a given area can be extended to all wind directions and speeds, and all likely sources and source locations using a new data structure called Dispersion Nomographs. Finally, we demonstrate a portable, entirely graphical software tool called CT-Analyst that embodies this entirely new, high-resolution technology and runs effectively on small personal computers. Real-time users don't have to wait for results because accurate answers are available with near zero-latency (that is 10 - 20 scenarios per second). Entire sequences of cases (e.g. a continuously changing source location or wind direction) can be computed and displayed as continuous-action movies. Since the underlying database has been precomputed, the door is wide open for important new real-time, zero-latency functions such as sensor data fusion, backtracking to an unknown source location, and even evacuation route planning. Extensions of the technology to sensor location optimization, buildings, tunnels, and integration with other advanced technologies, e.g. micrometeorology or detailed wind field measurements, will be discussed briefly here.

  17. Constraining the source location of the 30 May 2015 (Mw 7.9) Bonin deep-focus earthquake using seismogram envelopes of high-frequency P waveforms: Occurrence of deep-focus earthquake at the bottom of a subducting slab

    NASA Astrophysics Data System (ADS)

    Takemura, Shunsuke; Maeda, Takuto; Furumura, Takashi; Obara, Kazushige

    2016-05-01

    In this study, the source location of the 30 May 2015 (Mw 7.9) deep-focus Bonin earthquake was constrained using P wave seismograms recorded across Japan. We focus on propagation characteristics of high-frequency P wave. Deep-focus intraslab earthquakes typically show spindle-shaped seismogram envelopes with peak delays of several seconds and subsequent long-duration coda waves; however, both the main shock and aftershock of the 2015 Bonin event exhibited pulse-like P wave propagations with high apparent velocities (~12.2 km/s). Such P wave propagation features were reproduced by finite-difference method simulations of seismic wave propagation in the case of slab-bottom source. The pulse-like P wave seismogram envelopes observed from the 2015 Bonin earthquake show that its source was located at the bottom of the Pacific slab at a depth of ~680 km, rather than within its middle or upper regions.

  18. Estimating locations and total magnetization vectors of compact magnetic sources from scalar, vector, or tensor magnetic measurements through combined Helbig and Euler analysis

    USGS Publications Warehouse

    Phillips, J.D.; Nabighian, M.N.; Smith, D.V.; Li, Y.

    2007-01-01

    The Helbig method for estimating total magnetization directions of compact sources from magnetic vector components is extended so that tensor magnetic gradient components can be used instead. Depths of the compact sources can be estimated using the Euler equation, and their dipole moment magnitudes can be estimated using a least squares fit to the vector component or tensor gradient component data. ?? 2007 Society of Exploration Geophysicists.

  19. Geospatial simulation: an open-source, model-independent geospatial tool for managing point-based environmental models at multiple spatial locations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many point-based models have been designed to simulate hydrology, gas flux, nutrient dynamics, and/or plant growth processes at a single point on the landscape. However, these environmental processes are known to be spatially variable. Simulations at different spatial locations therefore require adj...

  20. Development and evaluation of a decision-supporting model for identifying the source location of microbial intrusions in real gravity sewer systems.

    PubMed

    Kim, Minyoung; Choi, Christopher Y; Gerba, Charles P

    2013-09-01

    Assuming a scenario of a hypothetical pathogenic outbreak, we aimed this study at developing a decision-support model for identifying the location of the pathogenic intrusion as a means of facilitating rapid detection and efficient containment. The developed model was applied to a real sewer system (the Campbell wash basin in Tucson, AZ) in order to validate its feasibility. The basin under investigation was divided into 14 sub-basins. The geometric information associated with the sewer network was digitized using GIS (Geological Information System) and imported into an urban sewer network simulation model to generate microbial breakthrough curves at the outlet. A pre-defined amount of Escherichia coli (E. coli), which is an indicator of fecal coliform bacteria, was hypothetically introduced into 56 manholes (four in each sub-basin, chosen at random), and a total of 56 breakthrough curves of E. coli were generated using the simulation model at the outlet. Transport patterns were classified depending upon the location of the injection site (manhole), various known characteristics (peak concentration and time, pipe length, travel time, etc.) extracted from each E. coli breakthrough curve and the layout of sewer network. Using this information, we back-predicted the injection location once an E. coli intrusion was detected at a monitoring site using Artificial Neural Networks (ANNs). The results showed that ANNs identified the location of the injection sites with 57% accuracy; ANNs correctly recognized eight out of fourteen expressions with relying on data from a single detection sensor. Increasing the available sensors within the basin significantly improved the accuracy of the simulation results (from 57% to 100%). PMID:23770478

  1. NHD INDEXED LOCATIONS FOR GRTS

    EPA Science Inventory

    GRTS locational data for nonpoint source projects. GRTS locations are coded onto route.drain (Transport and Coastline Reach) feature of NHD to create Point Events and Linear Events. GRTS locations are coded onto region.rch (Waterbody Reach) feature of NHD to create NHD Waterbody ...

  2. 40 CFR Table 2c to Subpart Zzzz of... - Requirements for Existing Compression Ignition Stationary RICE Located at a Major Source of HAP...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Standards for Hazardous Air Pollutants for Stationary Reciprocating Internal Combustion Engines Pt. 63... subpart. 3 Sources can petition the Administrator pursuant to the requirements of 40 CFR 63.6(g) for... as necessary.3 Minimize the engine's time spent at idle and minimize the engine's startup time...

  3. 40 CFR Table 2c to Subpart Zzzz of... - Requirements for Existing Compression Ignition Stationary RICE Located at a Major Source of HAP...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Standards for Hazardous Air Pollutants for Stationary Reciprocating Internal Combustion Engines Pt. 63... subpart. 3 Sources can petition the Administrator pursuant to the requirements of 40 CFR 63.6(g) for... as necessary.3 Minimize the engine's time spent at idle and minimize the engine's startup time...

  4. ACTRIS ACSM intercomparison - Part 2: Intercomparison of ME-2 organic source apportionment results from 15 individual, co-located aerosol mass spectrometers

    NASA Astrophysics Data System (ADS)

    Fröhlich, R.; Crenn, V.; Setyan, A.; Belis, C. A.; Canonaco, F.; Favez, O.; Riffault, V.; Slowik, J. G.; Aas, W.; Aijälä, M.; Alastuey, A.; Artiñano, B.; Bonnaire, N.; Bozzetti, C.; Bressi, M.; Carbone, C.; Coz, E.; Croteau, P. L.; Cubison, M. J.; Esser-Gietl, J. K.; Green, D. C.; Gros, V.; Heikkinen, L.; Herrmann, H.; Jayne, J. T.; Lunder, C. R.; Minguillón, M. C.; Močnik, G.; O'Dowd, C. D.; Ovadnevaite, J.; Petralia, E.; Poulain, L.; Priestman, M.; Ripoll, A.; Sarda-Estève, R.; Wiedensohler, A.; Baltensperger, U.; Sciare, J.; Prévôt, A. S. H.

    2015-06-01

    Chemically resolved atmospheric aerosol data sets from the largest intercomparison of the Aerodyne aerosol chemical speciation monitors (ACSMs) performed to date were collected at the French atmospheric supersite SIRTA. In total 13 quadrupole ACSMs (Q-ACSM) from the European ACTRIS ACSM network, one time-of-flight ACSM (ToF-ACSM), and one high-resolution ToF aerosol mass spectrometer (AMS) were operated in parallel for about 3 weeks in November and December~2013. Part 1 of this study reports on the accuracy and precision of the instruments for all the measured species. In this work we report on the intercomparison of organic components and the results from factor analysis source apportionment by positive matrix factorisation (PMF) utilising the multilinear engine 2 (ME-2). Except for the organic contribution of mass-to-charge ratio m/z 44 to the total organics (f44), which varied by factors between 0.6 and 1.3 compared to the mean, the peaks in the organic mass spectra were similar among instruments. The m/z 44 differences in the spectra resulted in a variable f44 in the source profiles extracted by ME-2, but had only a minor influence on the extracted mass contributions of the sources. The presented source apportionment yielded four factors for all 15 instruments: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA), biomass burning-related organic aerosol (BBOA) and secondary oxygenated organic aerosol (OOA). ME-2 boundary conditions (profile constraints) were optimised individually by means of correlation to external data in order to achieve equivalent / comparable solutions for all ACSM instruments and the results are discussed together with the investigation of the influence of alternative anchors (reference profiles). A comparison of the ME-2 source apportionment output of all 15 instruments resulted in relative standard deviations (SD) from the mean between 13.7 and 22.7 % of the source's average mass contribution depending on the

  5. Underwater hydrophone location survey

    NASA Technical Reports Server (NTRS)

    Cecil, Jack B.

    1993-01-01

    The Atlantic Undersea Test and Evaluation Center (AUTEC) is a U.S. Navy test range located on Andros Island, Bahamas, and a Division of the Naval Undersea Warfare Center (NUWC), Newport, RI. The Headquarters of AUTEC is located at a facility in West Palm Beach, FL. AUTEC's primary mission is to provide the U.S. Navy with a deep-water test and evaluation facility for making underwater acoustic measurements, testing and calibrating sonars, and providing accurate underwater, surface, and in-air tracking data on surface ships, submarines, aircraft, and weapon systems. Many of these programs are in support of Antisubmarine Warfare (ASW), undersea research and development programs, and Fleet assessment and operational readiness trials. Most tests conducted at AUTEC require precise underwater tracking (plus or minus 3 yards) of multiple acoustic signals emitted with the correct waveshape and repetition criteria from either a surface craft or underwater vehicle.

  6. Static and wind tunnel near-field/far-field jet noise measurements from model scale single-flow baseline and suppressor nozzles. Volume 1: Noise source locations and extrapolation of static free-field jet noise data

    NASA Technical Reports Server (NTRS)

    Jaeck, C. L.

    1976-01-01

    A test was conducted in the Boeing Large Anechoic Chamber to determine static jet noise source locations of six baseline and suppressor nozzle models, and establish a technique for extrapolating near field data into the far field. The test covered nozzle pressure ratios from 1.44 to 2.25 and jet velocities from 412 to 594 m/s at a total temperature of 844 K.

  7. NGC 5548: LACK OF A BROAD Fe K{alpha} LINE AND CONSTRAINTS ON THE LOCATION OF THE HARD X-RAY SOURCE

    SciTech Connect

    Brenneman, L. W.; Elvis, M.; Krongold, Y.; Liu, Y.; Mathur, S.

    2012-01-01

    We present an analysis of the co-added and individual 0.7-40 keV spectra from seven Suzaku observations of the Sy 1.5 galaxy NGC 5548 taken over a period of eight weeks. We conclude that the source has a moderately ionized, three-zone warm absorber, a power-law continuum, and exhibits contributions from cold, distant reflection. Relativistic reflection signatures are not significantly detected in the co-added data, and we place an upper limit on the equivalent width of a relativistically broad Fe K{alpha} line at EW {<=} 26 eV at 90% confidence. Thus NGC 5548 can be labeled as a 'weak' type 1 active galactic nucleus (AGN) in terms of its observed inner disk reflection signatures, in contrast to sources with very broad, strong iron lines such as MCG-6-30-15, which are likely much fewer in number. We compare physical properties of NGC 5548 and MCG-6-30-15 that might explain this difference in their reflection properties. Though there is some evidence that NGC 5548 may harbor a truncated inner accretion disk, this evidence is inconclusive, so we also consider light bending of the hard X-ray continuum emission in order to explain the lack of relativistic reflection in our observation. If the absence of a broad Fe K{alpha} line is interpreted in the light-bending context, we conclude that the source of the hard X-ray continuum lies at radii r{sub s} {approx}> 100 r{sub g}. We note, however, that light-bending models must be expanded to include a broader range of physical parameter space in order to adequately explain the spectral and timing properties of average AGNs, rather than just those with strong, broad iron lines.

  8. Location-assured, multifactor authentication on smartphones via LTE communication

    NASA Astrophysics Data System (ADS)

    Kuseler, Torben; Lami, Ihsan A.; Al-Assam, Hisham

    2013-05-01

    With the added security provided by LTE, geographical location has become an important factor for authentication to enhance the security of remote client authentication during mCommerce applications using Smartphones. Tight combination of geographical location with classic authentication factors like PINs/Biometrics in a real-time, remote verification scheme over the LTE layer connection assures the authenticator about the client itself (via PIN/biometric) as well as the client's current location, thus defines the important aspects of "who", "when", and "where" of the authentication attempt without eaves dropping or man on the middle attacks. To securely integrate location as an authentication factor into the remote authentication scheme, client's location must be verified independently, i.e. the authenticator should not solely rely on the location determined on and reported by the client's Smartphone. The latest wireless data communication technology for mobile phones (4G LTE, Long-Term Evolution), recently being rolled out in various networks, can be employed to enhance this location-factor requirement of independent location verification. LTE's Control Plane LBS provisions, when integrated with user-based authentication and independent source of localisation factors ensures secure efficient, continuous location tracking of the Smartphone. This feature can be performed during normal operation of the LTE-based communication between client and network operator resulting in the authenticator being able to verify the client's claimed location more securely and accurately. Trials and experiments show that such algorithm implementation is viable for nowadays Smartphone-based banking via LTE communication.

  9. A study of noise source location on a model scale augmentor wing using correlation techniques. [noise measurement of far field noise by wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Wilby, J. F.; Scharton, T. D.

    1975-01-01

    An experimental investigation, conducted on a model-scale augmentor wing to identify the sources of far-field noise, is examined. The measurement procedure followed in the investigation involved the cross-correlation of far field sound pressures with fluctuating pressures on the surface of the augmentor flap and shroud. In addition pressures on the surfaces of the augmentor were cross-correlated. The results are interpreted as showing that the surface pressure fluctuations are mainly aerodynamic in character and are convected in the downstream direction with a velocity which is dependent on the jet exhaust velocity. However the far field sound levels in the mid and high frequency ranges are dominated by jet noise. There is an indication that in the low frequency range trailing edge noise, associated with interaction of the jet flow and the flap trailing edge, plays a significant role in the radiated sound field.

  10. Integrated magnetic, gravity, and GPR surveys to locate the probable source of hydrocarbon contamination in Sharm El-Sheikh area, south Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Morsy, Mona; Rashed, Mohamed

    2013-01-01

    Sharm El-Sheikh waters were suddenly hit by hydrocarbon spills which created a serious threat to the prosperous tourism industry in and around the city. Analysis of soil samples, water samples, and seabed samples collected in and around the contaminated bay area showed anomalous levels of hydrocarbons. An integrated geophysical investigation, using magnetic, gravity, and ground penetrating radar geophysical tools, was conducted in the headland overlooking the contaminated bay in order to delineate the possible subsurface source of contamination. The results of the geophysical investigations revealed three underground manmade reinforced concrete tanks and a complicated network of buried steel pipes in addition to other unidentified buried objects. The depths and dimensions of the discovered objects were determined. Geophysical investigations also revealed the presence of a north-south oblique slip fault running through the eastern part of the studied area. Excavations, conducted later on, confirmed the presence of one of the tanks delineated by the geophysical surveys.

  11. Method and system for determining depth distribution of radiation-emitting material located in a source medium and radiation detector system for use therein

    DOEpatents

    Benke, Roland R.; Kearfott, Kimberlee J.; McGregor, Douglas S.

    2003-03-04

    A method, system and a radiation detector system for use therein are provided for determining the depth distribution of radiation-emitting material distributed in a source medium, such as a contaminated field, without the need to take samples, such as extensive soil samples, to determine the depth distribution. The system includes a portable detector assembly with an x-ray or gamma-ray detector having a detector axis for detecting the emitted radiation. The radiation may be naturally-emitted by the material, such as gamma-ray-emitting radionuclides, or emitted when the material is struck by other radiation. The assembly also includes a hollow collimator in which the detector is positioned. The collimator causes the emitted radiation to bend toward the detector as rays parallel to the detector axis of the detector. The collimator may be a hollow cylinder positioned so that its central axis is perpendicular to the upper surface of the large area source when positioned thereon. The collimator allows the detector to angularly sample the emitted radiation over many ranges of polar angles. This is done by forming the collimator as a single adjustable collimator or a set of collimator pieces having various possible configurations when connected together. In any one configuration, the collimator allows the detector to detect only the radiation emitted from a selected range of polar angles measured from the detector axis. Adjustment of the collimator or the detector therein enables the detector to detect radiation emitted from a different range of polar angles. The system further includes a signal processor for processing the signals from the detector wherein signals obtained from different ranges of polar angles are processed together to obtain a reconstruction of the radiation-emitting material as a function of depth, assuming, but not limited to, a spatially-uniform depth distribution of the material within each layer. The detector system includes detectors having

  12. CD34+ stromal cells/fibroblasts/fibrocytes/telocytes as a tissue reserve and a principal source of mesenchymal cells. Location, morphology, function and role in pathology.

    PubMed

    Díaz-Flores, L; Gutiérrez, R; García, M P; Sáez, F J; Díaz-Flores, L; Valladares, F; Madrid, J F

    2014-07-01

    We review the morphofunctional characteristics of CD34+ stromal fibroblastic/fibrocytic cells (CD34+ SFCs) and report our observations. We consider the following aspects of CD34+ SFCs: A) The confusing terms applied to this cell type, often combining the prefix CD34 with numerous names, including fibroblasts, fibrocytes, dendrocytes, keratocytes, telocytes and stromal, dendritic, adventitial, supraadventitial, perivascular, paravascular and delimiting cells; B) Changes in their immunophenotype, e.g., loss of CD34 expression and gain of other markers, such as those defining mesenchymal and derivate cells (myofibroblasts, osteoblasts, chondroblasts, adipocytes); C) Morphology (elongated or triangular cell body and thin, moniliform, bipolar or multipolar cytoplasmic processes), immunohistochemistry (co-expression of and changes in molecular expression) and structure (characteristics of nucleus and cytoplasmic organelles, and points of contact and junctions in quiescent and activated stages by light and electron microscopy); D) Location and distribution in the vessels (adventitia or external layer), in the tissues (connective, adipose, blood, muscle and nervous) and in the organs and systems (skin, oral cavity and oropharynx, respiratory, digestive, urinary, male, female, endocrine and lymphoid systems, serosal and synovial membranes, heart, eye and meninges); E) Origin from the mesoderm and cranial neural crest in the embryo, and from stem cells (themselves or other cells) and/or peripheral blood pluripotent stem cells (circulating progenitor cells) in post-natal life; F) Functions, such as synthesis of different molecules, progenitor of mesenchymal cells, immunomodulation, parenchymal regulation (growth, maturation and differentiation of adjacent cells), induction of angiogenesis, scaffolding support of other cells and phagocytic properties. Since CD34+ SFCs are the main reservoir of tissue mesenchymal cells (great mesenchymal potential, probably higher than that

  13. Automated microseismic event location using Master-Event Waveform Stacking.

    PubMed

    Grigoli, Francesco; Cesca, Simone; Krieger, Lars; Kriegerowski, Marius; Gammaldi, Sergio; Horalek, Josef; Priolo, Enrico; Dahm, Torsten

    2016-01-01

    Accurate and automated locations of microseismic events are desirable for many seismological and industrial applications. The analysis of microseismicity is particularly challenging because of weak seismic signals with low signal-to-noise ratio. Traditional location approaches rely on automated picking, based on individual seismograms, and make no use of the coherency information between signals at different stations. This strong limitation has been overcome by full-waveform location methods, which exploit the coherency of waveforms at different stations and improve the location robustness even in presence of noise. However, the performance of these methods strongly depend on the accuracy of the adopted velocity model, which is often quite rough; inaccurate models result in large location errors. We present an improved waveform stacking location method based on source-specific station corrections. Our method inherits the advantages of full-waveform location methods while strongly mitigating the dependency on the accuracy of the velocity model. With this approach the influence of an inaccurate velocity model on the results is restricted to the estimation of travel times solely within the seismogenic volume, but not for the entire source-receiver path. We finally successfully applied our new method to a realistic synthetic dataset as well as real data. PMID:27185465

  14. Automated microseismic event location using Master-Event Waveform Stacking

    NASA Astrophysics Data System (ADS)

    Grigoli, Francesco; Cesca, Simone; Krieger, Lars; Kriegerowski, Marius; Gammaldi, Sergio; Horalek, Josef; Priolo, Enrico; Dahm, Torsten

    2016-05-01

    Accurate and automated locations of microseismic events are desirable for many seismological and industrial applications. The analysis of microseismicity is particularly challenging because of weak seismic signals with low signal-to-noise ratio. Traditional location approaches rely on automated picking, based on individual seismograms, and make no use of the coherency information between signals at different stations. This strong limitation has been overcome by full-waveform location methods, which exploit the coherency of waveforms at different stations and improve the location robustness even in presence of noise. However, the performance of these methods strongly depend on the accuracy of the adopted velocity model, which is often quite rough; inaccurate models result in large location errors. We present an improved waveform stacking location method based on source-specific station corrections. Our method inherits the advantages of full-waveform location methods while strongly mitigating the dependency on the accuracy of the velocity model. With this approach the influence of an inaccurate velocity model on the results is restricted to the estimation of travel times solely within the seismogenic volume, but not for the entire source-receiver path. We finally successfully applied our new method to a realistic synthetic dataset as well as real data.

  15. Automated microseismic event location using Master-Event Waveform Stacking

    PubMed Central

    Grigoli, Francesco; Cesca, Simone; Krieger, Lars; Kriegerowski, Marius; Gammaldi, Sergio; Horalek, Josef; Priolo, Enrico; Dahm, Torsten

    2016-01-01

    Accurate and automated locations of microseismic events are desirable for many seismological and industrial applications. The analysis of microseismicity is particularly challenging because of weak seismic signals with low signal-to-noise ratio. Traditional location approaches rely on automated picking, based on individual seismograms, and make no use of the coherency information between signals at different stations. This strong limitation has been overcome by full-waveform location methods, which exploit the coherency of waveforms at different stations and improve the location robustness even in presence of noise. However, the performance of these methods strongly depend on the accuracy of the adopted velocity model, which is often quite rough; inaccurate models result in large location errors. We present an improved waveform stacking location method based on source-specific station corrections. Our method inherits the advantages of full-waveform location methods while strongly mitigating the dependency on the accuracy of the velocity model. With this approach the influence of an inaccurate velocity model on the results is restricted to the estimation of travel times solely within the seismogenic volume, but not for the entire source-receiver path. We finally successfully applied our new method to a realistic synthetic dataset as well as real data. PMID:27185465

  16. Dipole Well Location

    1998-08-03

    The problem here is to model the three-dimensional response of an electromagnetic logging tool to a practical situation which is often encountered in oil and gas exploration. The DWELL code provide the electromagnetic fields on the axis of a borehole due to either an electric or a magnetic dipole located on the same axis. The borehole is cylindrical, and is located within a stratified formation in which the bedding planes are not horizontal. The anglemore » between the normal to the bedding planes and the axis of the borehole may assume any value, or in other words, the borehole axis may be tilted with respect to the bedding planes. Additionally, all of the formation layers may have invasive zones of drilling mud. The operating frequency of the source dipole(s) extends from a few Hertz to hundreds of Megahertz.« less

  17. Dipole Well Location

    SciTech Connect

    Newman, Gregory

    1998-08-03

    The problem here is to model the three-dimensional response of an electromagnetic logging tool to a practical situation which is often encountered in oil and gas exploration. The DWELL code provide the electromagnetic fields on the axis of a borehole due to either an electric or a magnetic dipole located on the same axis. The borehole is cylindrical, and is located within a stratified formation in which the bedding planes are not horizontal. The angle between the normal to the bedding planes and the axis of the borehole may assume any value, or in other words, the borehole axis may be tilted with respect to the bedding planes. Additionally, all of the formation layers may have invasive zones of drilling mud. The operating frequency of the source dipole(s) extends from a few Hertz to hundreds of Megahertz.

  18. NNLOPS accurate associated HW production

    NASA Astrophysics Data System (ADS)

    Astill, William; Bizon, Wojciech; Re, Emanuele; Zanderighi, Giulia

    2016-06-01

    We present a next-to-next-to-leading order accurate description of associated HW production consistently matched to a parton shower. The method is based on reweighting events obtained with the HW plus one jet NLO accurate calculation implemented in POWHEG, extended with the MiNLO procedure, to reproduce NNLO accurate Born distributions. Since the Born kinematics is more complex than the cases treated before, we use a parametrization of the Collins-Soper angles to reduce the number of variables required for the reweighting. We present phenomenological results at 13 TeV, with cuts suggested by the Higgs Cross section Working Group.

  19. Acoustic gunshot location in complex environments: concepts and results

    NASA Astrophysics Data System (ADS)

    Showen, R. L.; Calhoun, R. B.; Chu, Wai C.; Dunham, J. W.

    2008-04-01

    A gunshot location system can be implemented in complex urban environments using a distributed array of acoustic sensors. A primary difficulty in computing the source location is that unknown path obstructions in the environment interfere with the reception of the sound at the sensor, by blocking the sound entirely, by refracting the path, or by creating echoes. Other complications are created by the similarity between gunshot sounds and other less interesting urban noises, frequency-dependent absorption of sound, and possible computational difficulty when multiple gunshots generate large data sets that stress real-time analysis routines. The ShotSpotter Gunshot Location System®1, deployed in over two dozen cities in the United States, detects and locates gunfire using a network of acoustic sensors placed on rooftops and utility poles, on moving vehicles, or on personnel. This sensor network, combined with a software system to collate and compute location results from the array of sensors, accurately locates gunshot sounds in complex urban environments. A classifier discards solutions incorporating non-gunshot audio pulses produced by the complex environment. Examples of difficult detection problems, including gunshots from a moving source, show that the detection and classification algorithms described are effective at recovering useful results from signals found in real-world urban scenarios.

  20. How to accurately bypass damage

    PubMed Central

    Broyde, Suse; Patel, Dinshaw J.

    2016-01-01

    Ultraviolet radiation can cause cancer through DNA damage — specifically, by linking adjacent thymine bases. Crystal structures show how the enzyme DNA polymerase η accurately bypasses such lesions, offering protection. PMID:20577203

  1. Accurate Evaluation of Quantum Integrals

    NASA Technical Reports Server (NTRS)

    Galant, David C.; Goorvitch, D.

    1994-01-01

    Combining an appropriate finite difference method with Richardson's extrapolation results in a simple, highly accurate numerical method for solving a Schr\\"{o}dinger's equation. Important results are that error estimates are provided, and that one can extrapolate expectation values rather than the wavefunctions to obtain highly accurate expectation values. We discuss the eigenvalues, the error growth in repeated Richardson's extrapolation, and show that the expectation values calculated on a crude mesh can be extrapolated to obtain expectation values of high accuracy.

  2. Quantifying Methane Fluxes Simply and Accurately: The Tracer Dilution Method

    NASA Astrophysics Data System (ADS)

    Rella, Christopher; Crosson, Eric; Green, Roger; Hater, Gary; Dayton, Dave; Lafleur, Rick; Merrill, Ray; Tan, Sze; Thoma, Eben

    2010-05-01

    Methane is an important atmospheric constituent with a wide variety of sources, both natural and anthropogenic, including wetlands and other water bodies, permafrost, farms, landfills, and areas with significant petrochemical exploration, drilling, transport, or processing, or refining occurs. Despite its importance to the carbon cycle, its significant impact as a greenhouse gas, and its ubiquity in modern life as a source of energy, its sources and sinks in marine and terrestrial ecosystems are only poorly understood. This is largely because high quality, quantitative measurements of methane fluxes in these different environments have not been available, due both to the lack of robust field-deployable instrumentation as well as to the fact that most significant sources of methane extend over large areas (from 10's to 1,000,000's of square meters) and are heterogeneous emitters - i.e., the methane is not emitted evenly over the area in question. Quantifying the total methane emissions from such sources becomes a tremendous challenge, compounded by the fact that atmospheric transport from emission point to detection point can be highly variable. In this presentation we describe a robust, accurate, and easy-to-deploy technique called the tracer dilution method, in which a known gas (such as acetylene, nitrous oxide, or sulfur hexafluoride) is released in the same vicinity of the methane emissions. Measurements of methane and the tracer gas are then made downwind of the release point, in the so-called far-field, where the area of methane emissions cannot be distinguished from a point source (i.e., the two gas plumes are well-mixed). In this regime, the methane emissions are given by the ratio of the two measured concentrations, multiplied by the known tracer emission rate. The challenges associated with atmospheric variability and heterogeneous methane emissions are handled automatically by the transport and dispersion of the tracer. We present detailed methane flux

  3. Impact of primary and secondary organic sources on the oxidative potential of quasi-ultrafine particles (PM0.25) at three contrasting locations in the Los Angeles Basin

    NASA Astrophysics Data System (ADS)

    Saffari, Arian; Hasheminassab, Sina; Wang, Dongbin; Shafer, Martin M.; Schauer, James J.; Sioutas, Constantinos

    2015-11-01

    To investigate the changing contribution of primary and secondary sources on the oxidative potential of particulate matter (PM) in a real-world urban atmosphere, 7 sets of quasi-ultrafine particles (PM0.25) were collected at three contrasting locations in the Los Angeles Basin, California, USA. Samples were collected in the coastal area of Long Beach during the morning rush hour period, representing fresh primary emissions from nearby freeways and the LA port; in central Los Angeles during midday, representing a mixture of fresh primary emissions and early products of photochemical secondary organic aerosol (SOA) formation; and at a downwind site (Upland) during afternoon, when the impacts of photochemically aged secondary PM are significant. Chemical composition showed distinctive trends, with the lowest fraction of water soluble organic carbon (WSOC) and other organic tracers of SOA formation (e.g. organic acids) at Long Beach, and the lowest abundance of organic tracers of primary vehicular emissions (such as polycyclic aromatic hydrocarbons and hopanes) at Upland. A molecular marker-based chemical mass balance (MM-CMB) model indicated that 72% of the total organic carbon at Long Beach was comprised of primary vehicular sources (combined heavy duty and light duty vehicles), while the vehicular fraction was found to be 50% and 39% at Los Angeles and Upland, respectively. Regression analysis suggested that at Long Beach, the variation in oxidative potential of PM0.25 (quantified using a macrophage-based reactive oxygen species (ROS) assay) was mainly driven by mobile vehicular emissions and the water-insoluble fraction of the organic carbon. In contrast, at Upland, where photochemical processing and secondary aerosol formation was the highest, WSOC and secondary organics were the major drivers of the oxidative potential variation. The multivariate regression analysis also indicated that as much as 58% of the overall spatial and temporal variation in the oxidative

  4. Pan-information Location Map

    NASA Astrophysics Data System (ADS)

    Zhu, X. Y.; Guo, W.; Huang, L.; Hu, T.; Gao, W. X.

    2013-11-01

    A huge amount of information, including geographic, environmental, socio-economic, personal and social network information, has been generated from diverse sources. Most of this information exists separately and is disorderly even if some of it is about the same person, feature, phenomenon or event. Users generally need to collect related information from different sources and then utilize them in applications. An automatic mechanism, therefore, for establishing a connection between potentially-related information will profoundly expand the usefulness of this huge body of information. A connection tie is semantic location describing semantically concepts and attributes of locations as well as relationships between locations, since 80% of information contains some kind of geographic reference but not all of geographic reference has explicit geographic coordinates. Semantic location is an orthogonal form of location representation which can be represented as domain ontology or UML format. Semantic location associates various kinds of information about a same object to provide timely information services according to users' demands, habits, preferences and applications. Based on this idea, a Pan-Information Location Map (PILM) is proposed as a new-style 4D map to associates semantic location-based information dynamically to organize and consolidate the locality and characteristics of corresponding features and events, and delivers on-demand information with a User-Adaptive Smart Display (UASD).

  5. 40 CFR 141.703 - Sampling locations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 141.703 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Treatment for Cryptosporidium Source Water Monitoring Requirements § 141.703 Sampling locations. (a) Systems required to conduct source water...

  6. 40 CFR 141.703 - Sampling locations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 141.703 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Treatment for Cryptosporidium Source Water Monitoring Requirements § 141.703 Sampling locations. (a) Systems required to conduct source water...

  7. 40 CFR 141.703 - Sampling locations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 141.703 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Treatment for Cryptosporidium Source Water Monitoring Requirements § 141.703 Sampling locations. (a) Systems required to conduct source water...

  8. Accurate phase-shift velocimetry in rock.

    PubMed

    Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R; Holmes, William M

    2016-06-01

    Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models. PMID:27111139

  9. Accurate phase-shift velocimetry in rock

    NASA Astrophysics Data System (ADS)

    Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R.; Holmes, William M.

    2016-06-01

    Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models.

  10. METHOD OF LOCATING GROUNDS

    DOEpatents

    Macleish, K.G.

    1958-02-11

    ABS>This patent presents a method for locating a ground in a d-c circult having a number of parallel branches connected across a d-c source or generator. The complete method comprises the steps of locating the ground with reference to the mildpoint of the parallel branches by connecting a potentiometer across the terminals of the circuit and connecting the slider of the potentiometer to ground through a current indicating instrument, adjusting the slider to right or left of the mildpoint so as to cause the instrument to indicate zero, connecting the terminal of the network which is farthest from the ground as thus indicated by the potentiometer to ground through a condenser, impressing a ripple voltage on the circuit, and then measuring the ripple voltage at the midpoint of each parallel branch to find the branch in which is the lowest value of ripple voltage, and then measuring the distribution of the ripple voltage along this branch to determine the point at which the ripple voltage drops off to zero or substantially zero due to the existence of a ground. The invention has particular application where a circuit ground is present which will disappear if the normal circuit voltage is removed.

  11. Accurately Mapping M31's Microlensing Population

    NASA Astrophysics Data System (ADS)

    Crotts, Arlin

    2004-07-01

    We propose to augment an existing microlensing survey of M31 with source identifications provided by a modest amount of ACS {and WFPC2 parallel} observations to yield an accurate measurement of the masses responsible for microlensing in M31, and presumably much of its dark matter. The main benefit of these data is the determination of the physical {or "einstein"} timescale of each microlensing event, rather than an effective {"FWHM"} timescale, allowing masses to be determined more than twice as accurately as without HST data. The einstein timescale is the ratio of the lensing cross-sectional radius and relative velocities. Velocities are known from kinematics, and the cross-section is directly proportional to the {unknown} lensing mass. We cannot easily measure these quantities without knowing the amplification, hence the baseline magnitude, which requires the resolution of HST to find the source star. This makes a crucial difference because M31 lens m ass determinations can be more accurate than those towards the Magellanic Clouds through our Galaxy's halo {for the same number of microlensing events} due to the better constrained geometry in the M31 microlensing situation. Furthermore, our larger survey, just completed, should yield at least 100 M31 microlensing events, more than any Magellanic survey. A small amount of ACS+WFPC2 imaging will deliver the potential of this large database {about 350 nights}. For the whole survey {and a delta-function mass distribution} the mass error should approach only about 15%, or about 6% error in slope for a power-law distribution. These results will better allow us to pinpoint the lens halo fraction, and the shape of the halo lens spatial distribution, and allow generalization/comparison of the nature of halo dark matter in spiral galaxies. In addition, we will be able to establish the baseline magnitude for about 50, 000 variable stars, as well as measure an unprecedentedly deta iled color-magnitude diagram and luminosity

  12. Accurate measurement of unsteady state fluid temperature

    NASA Astrophysics Data System (ADS)

    Jaremkiewicz, Magdalena

    2016-07-01

    In this paper, two accurate methods for determining the transient fluid temperature were presented. Measurements were conducted for boiling water since its temperature is known. At the beginning the thermometers are at the ambient temperature and next they are immediately immersed into saturated water. The measurements were carried out with two thermometers of different construction but with the same housing outer diameter equal to 15 mm. One of them is a K-type industrial thermometer widely available commercially. The temperature indicated by the thermometer was corrected considering the thermometers as the first or second order inertia devices. The new design of a thermometer was proposed and also used to measure the temperature of boiling water. Its characteristic feature is a cylinder-shaped housing with the sheath thermocouple located in its center. The temperature of the fluid was determined based on measurements taken in the axis of the solid cylindrical element (housing) using the inverse space marching method. Measurements of the transient temperature of the air flowing through the wind tunnel using the same thermometers were also carried out. The proposed measurement technique provides more accurate results compared with measurements using industrial thermometers in conjunction with simple temperature correction using the inertial thermometer model of the first or second order. By comparing the results, it was demonstrated that the new thermometer allows obtaining the fluid temperature much faster and with higher accuracy in comparison to the industrial thermometer. Accurate measurements of the fast changing fluid temperature are possible due to the low inertia thermometer and fast space marching method applied for solving the inverse heat conduction problem.

  13. Location, Location, Location: Development of Spatiotemporal Sequence Learning in Infancy

    ERIC Educational Resources Information Center

    Kirkham, Natasha Z.; Slemmer, Jonathan A.; Richardson, Daniel C.; Johnson, Scott P.

    2007-01-01

    We investigated infants' sensitivity to spatiotemporal structure. In Experiment 1, circles appeared in a statistically defined spatial pattern. At test 11-month-olds, but not 8-month-olds, looked longer at a novel spatial sequence. Experiment 2 presented different color/shape stimuli, but only the location sequence was violated during test;…

  14. Regional Location Calibration in Asia

    NASA Astrophysics Data System (ADS)

    Steck, L. K.; Hartse, H.; Aprea, C.; Franks, J.; Velasco, A.; Randall, G.; Bradley, C.; Begnaud, M.; Aguilar-Chang, J.

    2002-12-01

    This paper presents a spectrum of issues and efforts involved in improving seismic location performance worldwide. Our efforts are largely designed around providing validated, rigorously calibrated travel times, azimuths, and slownesses along with accurate error estimates. To do so entails a significant effort that includes data mining, data integration, database management, developing optimal 1-, 2-, and 3-D Earth models, using the Earth models to predict wave propagation, developing corrections and errors for travel times, azimuths, and slownesses, and validation of all products. Results presented here will focus on Asia. For the region around station MAKZ in north-central Asia we have looked at several tens of published 1-D velocity models. For each model, travel time calculations were performed, predictions for P and S arrivals were established, and the predicted times were compared to the observed. We will present best-fit models for tectonic provinces out to regional distances from MAKZ. Previous work has shown that Non-stationary Modified Bayesian Kriging of travel time residuals successfully improves regional seismic event location, and this method is being extended to calculate corrections for azimuth and slowness. The ability to krig over 3-D Earth models is also being implemented. In order to produce the most useful corrections, we require accurate ground truth. For this we are continuing efforts to create a location database consisting of the best available seismic event locations and the most accurate and precise travel times. Building this database relies on participation from universities, other NNSA laboratories, and contacts in private industry. Through the kriging procedure we are able to stabilize location algorithms, but the ultimate usefulness of the corrections themselves is directly related to the quality of the ground truth from which the corrections are derived. Indeed, epicentral mislocations from EvLoc using travel time correction

  15. Helicopter magnetic survey conducted to locate wells

    SciTech Connect

    Veloski, G.A.; Hammack, R.W.; Stamp, V.; Hall, R.; Colina, K.

    2008-07-01

    A helicopter magnetic survey was conducted in August 2007 over 15.6 sq mi at the Naval Petroleum Reserve No. 3’s (NPR-3) Teapot Dome Field near Casper, Wyoming. The survey’s purpose was to accurately locate wells drilled there during more than 90 years of continuous oilfield operation. The survey was conducted at low altitude and with closely spaced flight lines to improve the detection of wells with weak magnetic response and to increase the resolution of closely spaced wells. The survey was in preparation for a planned CO2 flood for EOR, which requires a complete well inventory with accurate locations for all existing wells. The magnetic survey was intended to locate wells missing from the well database and to provide accurate locations for all wells. The ability of the helicopter magnetic survey to accurately locate wells was accomplished by comparing airborne well picks with well locations from an intense ground search of a small test area.

  16. Concurrent and Accurate Short Read Mapping on Multicore Processors.

    PubMed

    Martínez, Héctor; Tárraga, Joaquín; Medina, Ignacio; Barrachina, Sergio; Castillo, Maribel; Dopazo, Joaquín; Quintana-Ortí, Enrique S

    2015-01-01

    We introduce a parallel aligner with a work-flow organization for fast and accurate mapping of RNA sequences on servers equipped with multicore processors. Our software, HPG Aligner SA (HPG Aligner SA is an open-source application. The software is available at http://www.opencb.org, exploits a suffix array to rapidly map a large fraction of the RNA fragments (reads), as well as leverages the accuracy of the Smith-Waterman algorithm to deal with conflictive reads. The aligner is enhanced with a careful strategy to detect splice junctions based on an adaptive division of RNA reads into small segments (or seeds), which are then mapped onto a number of candidate alignment locations, providing crucial information for the successful alignment of the complete reads. The experimental results on a platform with Intel multicore technology report the parallel performance of HPG Aligner SA, on RNA reads of 100-400 nucleotides, which excels in execution time/sensitivity to state-of-the-art aligners such as TopHat 2+Bowtie 2, MapSplice, and STAR. PMID:26451814

  17. Predict amine solution properties accurately

    SciTech Connect

    Cheng, S.; Meisen, A.; Chakma, A.

    1996-02-01

    Improved process design begins with using accurate physical property data. Especially in the preliminary design stage, physical property data such as density viscosity, thermal conductivity and specific heat can affect the overall performance of absorbers, heat exchangers, reboilers and pump. These properties can also influence temperature profiles in heat transfer equipment and thus control or affect the rate of amine breakdown. Aqueous-amine solution physical property data are available in graphical form. However, it is not convenient to use with computer-based calculations. Developed equations allow improved correlations of derived physical property estimates with published data. Expressions are given which can be used to estimate physical properties of methyldiethanolamine (MDEA), monoethanolamine (MEA) and diglycolamine (DGA) solutions.

  18. Accurate thickness measurement of graphene

    NASA Astrophysics Data System (ADS)

    Shearer, Cameron J.; Slattery, Ashley D.; Stapleton, Andrew J.; Shapter, Joseph G.; Gibson, Christopher T.

    2016-03-01

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.

  19. Distance scaling method for accurate prediction of slowly varying magnetic fields in satellite missions

    NASA Astrophysics Data System (ADS)

    Zacharias, Panagiotis P.; Chatzineofytou, Elpida G.; Spantideas, Sotirios T.; Capsalis, Christos N.

    2016-07-01

    In the present work, the determination of the magnetic behavior of localized magnetic sources from near-field measurements is examined. The distance power law of the magnetic field fall-off is used in various cases to accurately predict the magnetic signature of an equipment under test (EUT) consisting of multiple alternating current (AC) magnetic sources. Therefore, parameters concerning the location of the observation points (magnetometers) are studied towards this scope. The results clearly show that these parameters are independent of the EUT's size and layout. Additionally, the techniques developed in the present study enable the placing of the magnetometers close to the EUT, thus achieving high signal-to-noise ratio (SNR). Finally, the proposed method is verified by real measurements, using a mobile phone as an EUT.

  20. Location, location, location: the misprediction of satisfaction in housing lotteries.

    PubMed

    Dunn, Elizabeth W; Wilson, Timothy D; Gilbert, Daniel T

    2003-11-01

    People tend to overestimate the emotional consequences of future life events, exhibiting an impact bias. The authors replicated the impact bias in a real-life context in which undergraduates were randomly assigned to dormitories (or "houses"). Participants appeared to focus on the wrong factors when imagining their future happiness in the houses. They placed far greater weight on highly variable physical features than on less variable social features in predicting their future happiness in each house, despite accurately recognizing that social features were more important than physical features when asked explicitly about the determinants of happiness. In Experiment 2, we found that this discrepancy emerged in part because participants exhibited an isolation effect, focusing too much on factors that distinguished between houses and not enough on factors that varied only slightly, such as social features. PMID:15189579

  1. 45 CFR 303.3 - Location of noncustodial parents.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...; interstate location networks; local officials and employees administering public assistance, general assistance, medical assistance, food stamps and social services (whether such individuals are employed by the... appropriate location sources such as the Federal PLS; interstate location networks; local officials...

  2. Location, Location, Location: Where Do Location-Based Services Fit into Your Institution's Social Media Mix?

    ERIC Educational Resources Information Center

    Nekritz, Tim

    2011-01-01

    Foursquare is a location-based social networking service that allows users to share their location with friends. Some college administrators have been thinking about whether and how to take the leap into location-based services, which are also known as geosocial networking services. These platforms, which often incorporate gaming elements like…

  3. Accurate ab Initio Spin Densities

    PubMed Central

    2012-01-01

    We present an approach for the calculation of spin density distributions for molecules that require very large active spaces for a qualitatively correct description of their electronic structure. Our approach is based on the density-matrix renormalization group (DMRG) algorithm to calculate the spin density matrix elements as a basic quantity for the spatially resolved spin density distribution. The spin density matrix elements are directly determined from the second-quantized elementary operators optimized by the DMRG algorithm. As an analytic convergence criterion for the spin density distribution, we employ our recently developed sampling-reconstruction scheme [J. Chem. Phys.2011, 134, 224101] to build an accurate complete-active-space configuration-interaction (CASCI) wave function from the optimized matrix product states. The spin density matrix elements can then also be determined as an expectation value employing the reconstructed wave function expansion. Furthermore, the explicit reconstruction of a CASCI-type wave function provides insight into chemically interesting features of the molecule under study such as the distribution of α and β electrons in terms of Slater determinants, CI coefficients, and natural orbitals. The methodology is applied to an iron nitrosyl complex which we have identified as a challenging system for standard approaches [J. Chem. Theory Comput.2011, 7, 2740]. PMID:22707921

  4. Fault and partial discharge location systems for gas-insulated transmission lines. Final report

    SciTech Connect

    Boggs, S.A.; Ford, G.L.; Fujimoto, N.; Stone, G.C.

    1983-12-01

    Partial discharge and faults in gas-insulated transmission line (GITL) can be difficult to locate. This report describes the development, testing, and application of systems for fault and partial discharge location in GITL. Both systems are based on timing of electromagnetic transients generated by a fault/partial discharge source. Both systems employ microcomputers to facilitate automated data acquisition and analysis. The major problems solved in developing the fault location system were coupling of high frequency signals from and between phases and isolation of high voltage short risetime signals from high speed digital logic. The problems addressed in the partial discharge location project include handling a large number of pulses which may include noise, the large dynamic range of partial discharge induced transients (> 80 dB), and achieving an accurate correlation resolution of 2 ns.

  5. Accurate Inventories Of Irrigated Land

    NASA Technical Reports Server (NTRS)

    Wall, S.; Thomas, R.; Brown, C.

    1992-01-01

    System for taking land-use inventories overcomes two problems in estimating extent of irrigated land: only small portion of large state surveyed in given year, and aerial photographs made on 1 day out of year do not provide adequate picture of areas growing more than one crop per year. Developed for state of California as guide to controlling, protecting, conserving, and distributing water within state. Adapted to any large area in which large amounts of irrigation water needed for agriculture. Combination of satellite images, aerial photography, and ground surveys yields data for computer analysis. Analyst also consults agricultural statistics, current farm reports, weather reports, and maps. These information sources aid in interpreting patterns, colors, textures, and shapes on Landsat-images.

  6. Towards accurate and automatic morphing

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Sharkey, Paul M.

    2005-10-01

    Image morphing has proved to be a powerful tool for generating compelling and pleasing visual effects and has been widely used in entertainment industry. However, traditional image morphing methods suffer from a number of drawbacks: feature specification between images is tedious and the reliance on 2D information ignores the possible advantages to be gained from 3D knowledge. In this paper, we utilize recent advantages of computer vision technologies to diminish these drawbacks. By analyzing multi view geometry theories, we propose a processing pipeline based on three reference images. We first seek a few seed correspondences using robust methods and then recover multi view geometries using the seeds, through bundle adjustment. Guided by the recovered two and three view geometries, a novel line matching algorithm across three views is then deduced, through edge growth, line fitting and two and three view geometry constraints. Corresponding lines on a novel image is then obtained by an image transfer method and finally matched lines are fed into the traditional morphing methods and novel images are generated. Novel images generated by this pipeline have advantages over traditional morphing methods: they have an inherent 3D foundation and are therefore physically close to real scenes; not only images located between the baseline connecting two reference image centers, but also extrapolated images away from the baseline are possible; and the whole processing can be either wholly automatic, or at least the tedious task of feature specification in traditional morphing methods can be greatly relieved.

  7. Sarsat location algorithms

    NASA Astrophysics Data System (ADS)

    Nardi, Jerry

    The Satellite Aided Search and Rescue (Sarsat) is designed to detect and locate distress beacons using satellite receivers. Algorithms used for calculating the positions of 406 MHz beacons and 121.5/243 MHz beacons are presented. The techniques for matching, resolving and averaging calculated locations from multiple satellite passes are also described along with results pertaining to single pass and multiple pass location estimate accuracy.

  8. Reversible micromachining locator

    DOEpatents

    Salzer, Leander J.; Foreman, Larry R.

    1999-01-01

    This invention provides a device which includes a locator, a kinematic mount positioned on a conventional tooling machine, a part carrier disposed on the locator and a retainer ring. The locator has disposed therein a plurality of steel balls, placed in an equidistant position circumferentially around the locator. The kinematic mount includes a plurality of magnets which are in registry with the steel balls on the locator. In operation, a blank part to be machined is placed between a surface of a locator and the retainer ring (fitting within the part carrier). When the locator (with a blank part to be machined) is coupled to the kinematic mount, the part is thus exposed for the desired machining process. Because the locator is removably attachable to the kinematic mount, it can easily be removed from the mount, reversed, and reinserted onto the mount for additional machining. Further, the locator can likewise be removed from the mount and placed onto another tooling machine having a properly aligned kinematic mount. Because of the unique design and use of magnetic forces of the present invention, positioning errors of less than 0.25 micrometer for each machining process can be achieved.

  9. Reversible micromachining locator

    DOEpatents

    Salzer, L.J.; Foreman, L.R.

    1999-08-31

    This invention provides a device which includes a locator, a kinematic mount positioned on a conventional tooling machine, a part carrier disposed on the locator and a retainer ring. The locator has disposed therein a plurality of steel balls, placed in an equidistant position circumferentially around the locator. The kinematic mount includes a plurality of magnets which are in registry with the steel balls on the locator. In operation, a blank part to be machined is placed between a surface of a locator and the retainer ring (fitting within the part carrier). When the locator (with a blank part to be machined) is coupled to the kinematic mount, the part is thus exposed for the desired machining process. Because the locator is removably attachable to the kinematic mount, it can easily be removed from the mount, reversed, and reinserted onto the mount for additional machining. Further, the locator can likewise be removed from the mount and placed onto another tooling machine having a properly aligned kinematic mount. Because of the unique design and use of magnetic forces of the present invention, positioning errors of less than 0.25 micrometer for each machining process can be achieved. 7 figs.

  10. Assessment of User Home Location Geoinference Methods

    SciTech Connect

    Harrison, Joshua J.; Bell, Eric B.; Corley, Courtney D.; Dowling, Chase P.; Cowell, Andrew J.

    2015-05-29

    This study presents an assessment of multiple approaches to determine the home and/or other important locations to a Twitter user. In this study, we present a unique approach to the problem of geotagged data sparsity in social media when performing geoinferencing tasks. Given the sparsity of explicitly geotagged Twitter data, the ability to perform accurate and reliable user geolocation from a limited number of geotagged posts has proven to be quite useful. In our survey, we have achieved accuracy rates of over 86% in matching Twitter user profile locations with their inferred home locations derived from geotagged posts.

  11. System and Method of Locating Lightning Strikes

    NASA Technical Reports Server (NTRS)

    Medelius, Pedro J. (Inventor); Starr, Stanley O. (Inventor)

    2002-01-01

    A system and method of determining locations of lightning strikes has been described. The system includes multiple receivers located around an area of interest, such as a space center or airport. Each receiver monitors both sound and electric fields. The detection of an electric field pulse and a sound wave are used to calculate an area around each receiver in which the lighting is detected. A processor is coupled to the receivers to accurately determine the location of the lighting strike. The processor can manipulate the receiver data to compensate for environmental variables such as wind, temperature, and humidity. Further, each receiver processor can discriminate between distant and local lightning strikes.

  12. Towards an accurate bioimpedance identification

    NASA Astrophysics Data System (ADS)

    Sanchez, B.; Louarroudi, E.; Bragos, R.; Pintelon, R.

    2013-04-01

    This paper describes the local polynomial method (LPM) for estimating the time-invariant bioimpedance frequency response function (FRF) considering both the output-error (OE) and the errors-in-variables (EIV) identification framework and compare it with the traditional cross— and autocorrelation spectral analysis techniques. The bioimpedance FRF is measured with the multisine electrical impedance spectroscopy (EIS) technique. To show the overwhelming accuracy of the LPM approach, both the LPM and the classical cross— and autocorrelation spectral analysis technique are evaluated through the same experimental data coming from a nonsteady-state measurement of time-varying in vivo myocardial tissue. The estimated error sources at the measurement frequencies due to noise, σnZ, and the stochastic nonlinear distortions, σZNL, have been converted to Ω and plotted over the bioimpedance spectrum for each framework. Ultimately, the impedance spectra have been fitted to a Cole impedance model using both an unweighted and a weighted complex nonlinear least square (CNLS) algorithm. A table is provided with the relative standard errors on the estimated parameters to reveal the importance of which system identification frameworks should be used.

  13. Application of near real-time radial semblance to locate the shallow magmatic conduit at Kilauea Volcano, Hawaii

    USGS Publications Warehouse

    Dawson, P.; Whilldin, D.; Chouet, B.

    2004-01-01

    Radial Semblance is applied to broadband seismic network data to provide source locations of Very-Long-Period (VLP) seismic energy in near real time. With an efficient algorithm and adequate network coverage, accurate source locations of VLP energy are derived to quickly locate the shallow magmatic conduit system at Kilauea Volcano, Hawaii. During a restart in magma flow following a brief pause in the current eruption, the shallow magmatic conduit is pressurized, resulting in elastic radiation from various parts of the conduit system. A steeply dipping distribution of VLP hypocenters outlines a region extending from sea level to about 550 m elevation below and just east of the Halemaumau Pit Crater. The distinct hypocenters suggest the shallow plumbing system beneath Halemaumau consists of a complex plexus of sills and dikes. An unconstrained location for a section of the conduit is also observed beneath the region between Kilauea Caldera and Kilauea Iki Crater.

  14. Reverse radiance: a fast accurate method for determining luminance

    NASA Astrophysics Data System (ADS)

    Moore, Kenneth E.; Rykowski, Ronald F.; Gangadhara, Sanjay

    2012-10-01

    Reverse ray tracing from a region of interest backward to the source has long been proposed as an efficient method of determining luminous flux. The idea is to trace rays only from where the final flux needs to be known back to the source, rather than tracing in the forward direction from the source outward to see where the light goes. Once the reverse ray reaches the source, the radiance the equivalent forward ray would have represented is determined and the resulting flux computed. Although reverse ray tracing is conceptually simple, the method critically depends upon an accurate source model in both the near and far field. An overly simplified source model, such as an ideal Lambertian surface substantially detracts from the accuracy and thus benefit of the method. This paper will introduce an improved method of reverse ray tracing that we call Reverse Radiance that avoids assumptions about the source properties. The new method uses measured data from a Source Imaging Goniometer (SIG) that simultaneously measures near and far field luminous data. Incorporating this data into a fast reverse ray tracing integration method yields fast, accurate data for a wide variety of illumination problems.

  15. Location, location, location: finding a suitable home among the noise

    PubMed Central

    Stanley, Jenni A.; Radford, Craig A.; Jeffs, Andrew G.

    2012-01-01

    While sound is a useful cue for guiding the onshore orientation of larvae because it travels long distances underwater, it also has the potential to convey valuable information about the quality and type of the habitat at the source. Here, we provide, to our knowledge, the first evidence that settlement-stage coastal crab species can interpret and show a strong settlement and metamorphosis response to habitat-related differences in natural underwater sound. Laboratory- and field-based experiments demonstrated that time to metamorphosis in the settlement-stage larvae of common coastal crab species varied in response to different underwater sound signatures produced by different habitat types. The megalopae of five species of both temperate and tropical crabs showed a significant decrease in time to metamorphosis, when exposed to sound from their optimal settlement habitat type compared with other habitat types. These results indicate that sounds emanating from specific underwater habitats may play a major role in determining spatial patterns of recruitment in coastal crab species. PMID:22673354

  16. Location, location, location: finding a suitable home among the noise.

    PubMed

    Stanley, Jenni A; Radford, Craig A; Jeffs, Andrew G

    2012-09-01

    While sound is a useful cue for guiding the onshore orientation of larvae because it travels long distances underwater, it also has the potential to convey valuable information about the quality and type of the habitat at the source. Here, we provide, to our knowledge, the first evidence that settlement-stage coastal crab species can interpret and show a strong settlement and metamorphosis response to habitat-related differences in natural underwater sound. Laboratory- and field-based experiments demonstrated that time to metamorphosis in the settlement-stage larvae of common coastal crab species varied in response to different underwater sound signatures produced by different habitat types. The megalopae of five species of both temperate and tropical crabs showed a significant decrease in time to metamorphosis, when exposed to sound from their optimal settlement habitat type compared with other habitat types. These results indicate that sounds emanating from specific underwater habitats may play a major role in determining spatial patterns of recruitment in coastal crab species. PMID:22673354

  17. Object locating system

    DOEpatents

    Novak, James L.; Petterson, Ben

    1998-06-09

    A sensing system locates an object by sensing the object's effect on electric fields. The object's effect on the mutual capacitance of electrode pairs varies according to the distance between the object and the electrodes. A single electrode pair can sense the distance from the object to the electrodes. Multiple electrode pairs can more precisely locate the object in one or more dimensions.

  18. Reversible micromachining locator

    SciTech Connect

    Salzer, Leander J.; Foreman, Larry R.

    2002-01-01

    A locator with a part support is used to hold a part onto the kinematic mount of a tooling machine so that the part can be held in or replaced in exactly the same position relative to the cutting tool for machining different surfaces of the part or for performing different machining operations on the same or different surfaces of the part. The locator has disposed therein a plurality of steel balls placed at equidistant positions around the planar surface of the locator and the kinematic mount has a plurality of magnets which alternate with grooves which accommodate the portions of the steel balls projecting from the locator. The part support holds the part to be machined securely in place in the locator. The locator can be easily detached from the kinematic mount, turned over, and replaced onto the same kinematic mount or another kinematic mount on another tooling machine without removing the part to be machined from the locator so that there is no need to touch or reposition the part within the locator, thereby assuring exact replication of the position of the part in relation to the cutting tool on the tooling machine for each machining operation on the part.

  19. Reconstructing Spatial Distributions from Anonymized Locations

    SciTech Connect

    Horey, James L; Forrest, Stephanie; Groat, Michael

    2012-01-01

    Devices such as mobile phones, tablets, and sensors are often equipped with GPS that accurately report a person's location. Combined with wireless communication, these devices enable a wide range of new social tools and applications. These same qualities, however, leave location-aware applications vulnerable to privacy violations. This paper introduces the Negative Quad Tree, a privacy protection method for location aware applications. The method is broadly applicable to applications that use spatial density information, such as social applications that measure the popularity of social venues. The method employs a simple anonymization algorithm running on mobile devices, and a more complex reconstruction algorithm on a central server. This strategy is well suited to low-powered mobile devices. The paper analyzes the accuracy of the reconstruction method in a variety of simulated and real-world settings and demonstrates that the method is accurate enough to be used in many real-world scenarios.

  20. Microseismic response characteristics modeling and locating of underground water supply pipe leak

    NASA Astrophysics Data System (ADS)

    Wang, J.; Liu, J.

    2015-12-01

    In traditional methods of pipeline leak location, geophones must be located on the pipe wall. If the exact location of the pipeline is unknown, the leaks cannot be identified accurately. To solve this problem, taking into account the characteristics of the pipeline leak, we propose a continuous random seismic source model and construct geological models to investigate the proposed method for locating underground pipeline leaks. Based on two dimensional (2D) viscoacoustic equations and the staggered grid finite-difference (FD) algorithm, the microseismic wave field generated by a leaking pipe is modeled. Cross-correlation analysis and the simulated annealing (SA) algorithm were utilized to obtain the time difference and the leak location. We also analyze and discuss the effect of the number of recorded traces, the survey layout, and the offset and interval of the traces on the accuracy of the estimated location. The preliminary results of the simulation and data field experiment indicate that (1) a continuous random source can realistically represent the leak microseismic wave field in a simulation using 2D visco-acoustic equations and a staggered grid FD algorithm. (2) The cross-correlation method is effective for calculating the time difference of the direct wave relative to the reference trace. However, outside the refraction blind zone, the accuracy of the time difference is reduced by the effects of the refracted wave. (3) The acquisition method of time difference based on the microseismic theory and SA algorithm has a great potential for locating leaks from underground pipelines from an array located on the ground surface. Keywords: Viscoacoustic finite-difference simulation; continuous random source; simulated annealing algorithm; pipeline leak location

  1. Joint Determination of Event Location and Magnitude from Historical Seismic Damage Records

    NASA Astrophysics Data System (ADS)

    Park, S.; Hong, T. K.

    2014-12-01

    Large earthquakes have long recurrence intervals. It is crucial to consider long-time seismicity for a proper assessment of potential seismic hazards. It is required to use historical earthquake records to complement the long-time seismicity records. Historical earthquake records remain as in seismic damage description with limited accuracy in source parameters including event location and its size. It is important to determine epicenters and magnitudes of historical earthquakes accurately. A noble method to determine the event location and magnitude from historical seismic damage records is introduced. Seismic damage is typically proportional to the event magnitude, and is inversely proportional to the distance. This feature allows us to deduce the event magnitude and location from spatial distribution of seismic intensities. However, the magnitude and distance trade off each other, inhibiting unique determination of event magnitude and location. The Gutenberg-Richter frequency-magnitude relationship is additionally considered to constrain the source parameters. The Gutenberg-Richter frequency-magnitude relationship is assumed to be consistent between instrumental and historical seismicity. A set of event location and magnitude that satisfy the chance of event occurrence according to the Gutenberg-Richter frequency-magnitude relationship is selected. The accuracy of the method is tested for synthetic data sets, and the validity of the method is examined. The synthetic tests present high accuracy of the method. The method is applied to historical seismic damage records, which allows us to calibrate the source parameters of historical earthquakes.

  2. How Accurate are SuperCOSMOS Positions?

    NASA Astrophysics Data System (ADS)

    Schaefer, Adam; Hunstead, Richard; Johnston, Helen

    2014-02-01

    Optical positions from the SuperCOSMOS Sky Survey have been compared in detail with accurate radio positions that define the second realisation of the International Celestial Reference Frame (ICRF2). The comparison was limited to the IIIaJ plates from the UK/AAO and Oschin (Palomar) Schmidt telescopes. A total of 1 373 ICRF2 sources was used, with the sample restricted to stellar objects brighter than BJ = 20 and Galactic latitudes |b| > 10°. Position differences showed an rms scatter of 0.16 arcsec in right ascension and declination. While overall systematic offsets were < 0.1 arcsec in each hemisphere, both the systematics and scatter were greater in the north.

  3. Sensors Locate Radio Interference

    NASA Technical Reports Server (NTRS)

    2009-01-01

    After receiving a NASA Small Business Innovation Research (SBIR) contract from Kennedy Space Center, Soneticom Inc., based in West Melbourne, Florida, created algorithms for time difference of arrival and radio interferometry, which it used in its Lynx Location System (LLS) to locate electromagnetic interference that can disrupt radio communications. Soneticom is collaborating with the Federal Aviation Administration (FAA) to install and test the LLS at its field test center in New Jersey in preparation for deploying the LLS at commercial airports. The software collects data from each sensor in order to compute the location of the interfering emitter.

  4. Nonpoint sources

    SciTech Connect

    Selzer, L.

    1994-12-31

    Nonpoint source pollution remains the most pervasive water quality issue faced today. Unlike pollution from point sources, nonpoint source pollution is diffuse both in terms of its origin and the manner in which it enters ground and surface waters. It results from a great variety of human activities that take place over a wide geographic area perhaps many hundreds or even thousands of acres. And unlike pollutants from point sources--which enter the environment at well-defined locations and in relatively even, continuous discharges--pollutants from nonpoint sources usually find their way into surface and ground waters in sudden surges associated with rainfall, thunderstorms, or snowmelt. The author discusses some of the most significant sources of nonpoint source pollution.

  5. Antarctic Meteorite Location Map Series

    NASA Technical Reports Server (NTRS)

    Schutt, John (Editor); Fessler, Brian (Editor); Cassidy, William (Editor)

    1989-01-01

    Antarctica has been a prolific source of meteorites since meteorite concentrations were discovered in 1969. The Antarctic Search For Meteorites (ANSMET) project has been active over much of the Trans-Antarctic Mountain Range. The first ANSMET expedition (a joint U.S.-Japanese effort) discovered what turned out to be a significant concentration of meteorites at the Allan Hills in Victoria Land. Later reconnaissance in this region resulted in the discovery of meteorite concentrations on icefields to the west of the Allan Hills, at Reckling Moraine, and Elephant Moraine. Antarctic meteorite location maps (reduced versions) of the Allan Hills main, near western, middle western, and far western icefields and the Elephant Moraine icefield are presented. Other Antarctic meteorite location maps for the specimens found by the ANSMET project are being prepared.

  6. Lunar Impact Flash Locations

    NASA Technical Reports Server (NTRS)

    Moser, D. E.; Suggs, R. M.; Kupferschmidt, L.; Feldman, J.

    2015-01-01

    A bright impact flash detected by the NASA Lunar Impact Monitoring Program in March 2013 brought into focus the importance of determining the impact flash location. A process for locating the impact flash, and presumably its associated crater, was developed using commercially available software tools. The process was successfully applied to the March 2013 impact flash and put into production on an additional 300 impact flashes. The goal today: provide a description of the geolocation technique developed.

  7. Infrared horizon locator

    NASA Technical Reports Server (NTRS)

    Jalink, A., Jr. (Inventor)

    1973-01-01

    A precise method and apparatus for locating the earth's infrared horizon from space that is independent of season and latitude is described. First and second integrations of the earth's radiance profile are made from space to earth with the second delayed with respect to the first. The second integration is multiplied by a predetermined constant R and then compared with the first integration. When the two are equal the horizon is located.

  8. Object locating system

    DOEpatents

    Novak, J.L.; Petterson, B.

    1998-06-09

    A sensing system locates an object by sensing the object`s effect on electric fields. The object`s effect on the mutual capacitance of electrode pairs varies according to the distance between the object and the electrodes. A single electrode pair can sense the distance from the object to the electrodes. Multiple electrode pairs can more precisely locate the object in one or more dimensions. 12 figs.

  9. Optical sensor for detection of supercavity-body contact location

    NASA Astrophysics Data System (ADS)

    Belden, Jesse; Jandron, Michael; Truscott, Tadd

    2013-11-01

    Supercavitating vehicles have been the subject of intense research due to the potential for drag reduction and/or increased speeds. The control of such vehicles depends on accurate knowledge of planing forces generated by partial, transient wetting of afterbody surfaces. Measurement of the supercavity-body contact location, which determines the planing area, is thus critical for vehicle control. A robust sensor capable of measuring supercavity contact location along the length of a body is presented. The sensor operates on the optical principle of total internal reflection to differentiate between liquid and gas phases in contact with the body. An array of photodetectors is used to sense the presence or absence of light from a laser source to map the contact location. The theoretical operation and limitations of the sensor are discussed and several experiments are presented to validate the theory. Also, we present an elegant signal processing method to compensate for in situ changes in ambient light conditions. This work was funded by the Office of Naval Research.

  10. Accuracy of locating circular features using machine vision

    NASA Astrophysics Data System (ADS)

    Sklair, Cheryl W.; Hoff, William A.; Gatrell, Lance B.

    1992-03-01

    The ability to automatically locate objects using vision is a key technology for flexible, intelligent robotic operations. The vision task is facilitated by placing optical targets or markings in advance on the objects to be located. A number of researchers have advocated the use of circular target features as the features that can be most accurately located. This paper describes extensive analysis on circle centroid accuracy using both simulations and laboratory measurements. The work was part of an effort to design a video positioning sensor for NASA's Flight Telerobotic Servicer that would meet accuracy requirements. We have analyzed the main contributors to centroid error and have classified them into the following: (1) spatial quantization errors, (2) errors due to signal noise and random timing errors, (3) surface tilt errors, and (4) errors in modeling camera geometry. It is possible to compensate for the errors in (3) given an estimate of the tilt angle, and the errors from (4) by calibrating the intrinsic camera attributes. The errors in (1) and (2) cannot be compensated for, but they can be measured and their effects reduced somewhat. To characterize these error sources, we measured centroid repeatability under various conditions, including synchronization method, signal-to-noise ratio, and frequency attenuation. Although these results are specific to our video system and equipment, they provide a reference point that should be a characteristic of typical CCD cameras and digitization equipment.

  11. Deep space target location with Hubble Space Telescope (HST) and Hipparcos data

    NASA Technical Reports Server (NTRS)

    Null, George W.

    1988-01-01

    Interplanetary spacecraft navigation requires accurate a priori knowledge of target positions. A concept is presented for attaining improved target ephemeris accuracy using two future Earth-orbiting optical observatories, the European Space Agency (ESA) Hipparcos observatory and the Nasa Hubble Space Telescope (HST). Assuming nominal observatory performance, the Hipparcos data reduction will provide an accurate global star catalog, and HST will provide a capability for accurate angular measurements of stars and solar system bodies. The target location concept employs HST to observe solar system bodies relative to Hipparcos catalog stars and to determine the orientation (frame tie) of these stars to compact extragalactic radio sources. The target location process is described, the major error sources discussed, the potential target ephemeris error predicted, and mission applications identified. Preliminary results indicate that ephemeris accuracy comparable to the errors in individual Hipparcos catalog stars may be possible with a more extensive HST observing program. Possible future ground and spacebased replacements for Hipparcos and HST astrometric capabilities are also discussed.

  12. Commissural Gain Control Enhances the Midbrain Representation of Sound Location

    PubMed Central

    Orton, Llwyd David; Papasavvas, Christoforos A.

    2016-01-01

    Accurate localization of sound sources is essential for survival behavior in many species. The inferior colliculi (ICs) are the first point in the auditory pathway where cues used to locate sounds, ie, interaural time differences (ITDs), interaural level differences (ILDs), and pinna spectral cues, are all represented in the same location. These cues are first extracted separately on each side of the midline in brainstem nuclei that project to the ICs. Because of this segregation, each IC predominantly represents stimuli in the contralateral hemifield. We tested the hypothesis that commissural connections between the ICs mediate gain control that enhances sound localization acuity. We recorded IC neurons sensitive to either ITDs or ILDs in anesthetized guinea pig, before, during, and following recovery from deactivation of the contralateral IC by cryoloop cooling or microdialysis of procaine. During deactivation, responses were rescaled by divisive gain change and additive shifts, which reduced the dynamic range of ITD and ILD response functions and the ability of neurons to signal changes in sound location. These data suggest that each IC exerts multiplicative gain control and subtractive shifts over the other IC that enhances the neural representation of sound location. Furthermore, this gain control operates in a similar manner on both ITD- and ILD-sensitive neurons, suggesting a shared mechanism operates across localization cues. Our findings reveal a novel dependence of sound localization on commissural processing. SIGNIFICANCE STATEMENT Sound localization, a fundamental process in hearing, is dependent on bilateral computations in the brainstem. How this information is transmitted from the brainstem to the auditory cortex, through several stages of processing, without loss of signal fidelity, is not clear. We show that the ability of neurons in the auditory midbrain to encode azimuthal sound location is dependent on gain control mediated by the commissure of

  13. Marine cable location system

    SciTech Connect

    Zachariadis, R.G.

    1984-05-01

    An acoustic positioning system locates a marine cable at an exploration site, such cable employing a plurality of hydrophones at spaced-apart positions along the cable. A marine vessel measures water depth to the cable as the vessel passes over the cable and interrogates the hydrophones with sonar pulses along a slant range as the vessel travels in a parallel and horizontally offset path to the cable. The location of the hydrophones is determined from the recordings of water depth and slant range.

  14. Cable fault locator research

    NASA Astrophysics Data System (ADS)

    Cole, C. A.; Honey, S. K.; Petro, J. P.; Phillips, A. C.

    1982-07-01

    Cable fault location and the construction of four field test units are discussed. Swept frequency sounding of mine cables with RF signals was the technique most thoroughly investigated. The swept frequency technique is supplemented with a form of moving target indication to provide a method for locating the position of a technician along a cable and relative to a suspected fault. Separate, more limited investigations involved high voltage time domain reflectometry and acoustical probing of mine cables. Particular areas of research included microprocessor-based control of the swept frequency system, a microprocessor based fast Fourier transform for spectral analysis, and RF synthesizers.

  15. RFI emitter location techniques

    NASA Technical Reports Server (NTRS)

    Rao, B. L. J.

    1973-01-01

    The possibility is discussed of using Doppler techniques for determining the location of ground based emitters causing radio frequency interference with low orbiting satellites. An error analysis indicates that it is possible to find the emitter location within an error range of 2 n.mi. The parameters which determine the required satellite receiver characteristic are discussed briefly along with the non-real time signal processing which may by used in obtaining the Doppler curve. Finally, the required characteristics of the satellite antenna are analyzed.

  16. URANIUM MINE LOCATION DATABASE

    EPA Science Inventory

    EPA's Radiation Protection Division works to address hazards posed by technologically enhanced naturally occurring radioactive materials (TENORM). As one part of EPA's efforts to characterize risk from TENORM sources and to identify where TENORM problems exist, we have been inve...

  17. Accuracy of teleseismic event locations in the Middle East and North Africa

    SciTech Connect

    Sweeney, J.J.

    1996-12-04

    Seismic characterization at the regional level requires accurate determination of phases and travel times for many combinations of stations and events. An important consideration in the process is the accuracy of event locations. The LLNL Comprehensive Test Ban Treaty Research Program is currently working on data from the Middle East and North Africa, where seismic station coverage is relatively sparse and ``ground truth`` seismic source information is practically nonexistent. In this report the investigator use after shock studies as a source of local ground truth. He evaluates teleseismic location accuracy by comparing hypocenters determined by local networks with those determined teleseismically [e.g. the International Seismological Center (ISC) and the National Earthquake Information Center (NEIC)]. Epicentral locations, origin times, and depth determinations of events from three aftershocks studies (Algeria, Armenia, and Iran) and one local network study (Iran) are compared with ISC and NEIC locations for the same events. The key parameter for the ISC locations is the number of observations used in the location determination. For more than 40-50 observations, the agreement rapidly diminishes and ISC locations can differ from local determinations by as much as 80 km or more. Events in Iran show a distinct bias of ISC location errors toward the northeast; events in Armenia and Algeria show no directional bias. This study shows that only events with ISC M{sub b} {gt} 4.4-4.5 or NEIS M{sub b} {gt} 4.7-4. should be used for compiling travel time information from teleseismic bulletins in the Middle East/North Africa region when locations from the NEIC and ISC bulletins are used.

  18. Time-reversal imaging techniques applied to tremor waveforms near Cholame, California to locate tectonic tremor

    NASA Astrophysics Data System (ADS)

    Horstmann, T.; Harrington, R. M.; Cochran, E. S.

    2012-12-01

    Thurber et al. (2006) interpolated to a grid spacing of 50 m. Such grid spacing corresponds to frequencies of up to 8 Hz, which is suitable to calculate the wave propagation of tremor. Our dataset contains continuous broadband data from 13 STS-2 seismometers deployed from May 2010 to July 2011 along the Cholame segment of the San Andreas Fault as well as data from the HRSN and PBO networks. Initial synthetic results from tests on a 2D plane using a line of 15 receivers suggest that we are able to recover accurate event locations to within 100 m horizontally and 300 m depth. We conduct additional synthetic tests to determine the influence of signal-to-noise ratio, number of stations used, and the uncertainty in the velocity model on the location result by adding noise to the seismograms and perturbations to the velocity model. Preliminary results show accurate show location results to within 400 m with a median signal-to-noise ratio of 3.5 and 5% perturbations in the velocity model. The next steps will entail performing the synthetic tests on the 3D velocity model, and applying the method to tremor waveforms. Furthermore, we will determine the spatial and temporal distribution of the source locations and compare our results to those by Sumy and others.

  19. Particle impact location detector

    NASA Technical Reports Server (NTRS)

    Auer, S. O.

    1974-01-01

    Detector includes delay lines connected to each detector surface strip. When several particles strike different strips simultaneously, pulses generated by each strip are time delayed by certain intervals. Delay time for each strip is known. By observing time delay in pulse, it is possible to locate strip that is struck by particle.

  20. LOCATING AREAS OF CONCERN

    EPA Science Inventory

    A simple method to locate changes in vegetation cover, which can be used to identify areas under stress. The method only requires inexpensive NDVI data. The use of remotely sensed data is far more cost-effective than field studies and can be performed more quickly. Local knowledg...

  1. Location of Spirit's Home

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image shows where Earth would set on the martian horizon from the perspective of the Mars Exploration Rover Spirit if it were facing northwest atop its lander at Gusev Crater. Earth cannot be seen in this image, but engineers have mapped its location. This image mosaic was taken by the hazard-identification camera onboard Spirit.

  2. Precisely locating the Klamath Falls, Oregon, earthquakes

    USGS Publications Warehouse

    Qamar, A.; Meagher, K.L.

    1993-01-01

    In this article we present preliminary results of a close-in, instrumental study of the Klamath Falls earthquake sequence, carried as a cooperative effort by scientists from the U.S Geological Survey (USGS) and universities in Washington, Orgeon, and California. In addition to obtaining much mroe accurate earthquake locations, this study has improved our understanding of the relationship between seismicity and mapped faults in the region. 

  3. Substance Abuse Treatment Facility Locator

    MedlinePlus

    ... Health Services Locator Buprenorphine Physician Locator Find a Facility in Your State To locate the drug and ... Service . Privacy Policy . Home | About the Locator | Find Facilities Near You | Find Facilities by City, County, State ...

  4. Geoacoustic and source tracking using particle filtering: experimental results.

    PubMed

    Yardim, Caglar; Gerstoft, Peter; Hodgkiss, William S

    2010-07-01

    A particle filtering (PF) approach is presented for performing sequential geoacoustic inversion of a complex ocean acoustic environment using a moving acoustic source. This approach treats both the environmental parameters [e.g., water column sound speed profile (SSP), water depth, sediment and bottom parameters] at the source location and the source parameters (e.g., source depth, range and speed) as unknown random variables that evolve as the source moves. This allows real-time updating of the environment and accurate tracking of the moving source. As a sequential Monte Carlo technique that operates on nonlinear systems with non-Gaussian probability densities, the PF is an ideal algorithm to perform tracking of environmental and source parameters, and their uncertainties via the evolving posterior probability densities. The approach is demonstrated on both simulated data in a shallow water environment with a sloping bottom and experimental data collected during the SWellEx-96 experiment. PMID:20649203

  5. Identification of Impact Location in a Plate Based on Elastodynamics and Higher Order Time Frequency Method

    NASA Astrophysics Data System (ADS)

    Lee, S. K.; Kim, S. J.

    In a nuclear power plant, impact force due to loose part is related to the structural damage in the plant. In general, the steam generator of the nuclear power plant is structured by thick plate. The paper presents a novel approach to locate an impact load in a thick plate. The approach is based on the analysis of the acoustic waveforms measured by a sensor array located on the plate surface. For accurate estimation of the location of the impact source, the time differences in the arrival times of the waves at the sensors and their propagation velocities are determined. The dispersion curves for multi modes of Lamb wave are calculated by using exact plate theory and SDPT. It is difficult to measure directly the group velocity for Lamb mode of acoustic waveform in the thick plate because they are dispersive wave. However, most of the energy in the wave is carried by the flexural waves (A0 mode), the group velocity of this mode is extracted using the CHOTF technique for estimating the impact source location. The estimates are shown to be in excellent agreement with the actual locations and it is applied to the damage analysis due to the loose part in a nuclear power plant.

  6. Electric current locator

    DOEpatents

    King, Paul E.; Woodside, Charles Rigel

    2012-02-07

    The disclosure herein provides an apparatus for location of a quantity of current vectors in an electrical device, where the current vector has a known direction and a known relative magnitude to an input current supplied to the electrical device. Mathematical constants used in Biot-Savart superposition equations are determined for the electrical device, the orientation of the apparatus, and relative magnitude of the current vector and the input current, and the apparatus utilizes magnetic field sensors oriented to a sensing plane to provide current vector location based on the solution of the Biot-Savart superposition equations. Description of required orientations between the apparatus and the electrical device are disclosed and various methods of determining the mathematical constants are presented.

  7. Marine cable location system

    SciTech Connect

    Ottsen, H.; Barker, Th.

    1985-04-23

    An acoustic positioning system for locating a marine cable at an exploration site employs a plurality of acoustic transponders, each having a characteristic frequency, at spaced-apart positions along the cable. A marine vessel measures the depth to the transponders as the vessel passes over the cable and measures the slant range from the vessel to each of the acoustic transponders as the vessel travels in a parallel and horizontally offset path to the cable.

  8. Magnetic Location Indicator

    NASA Technical Reports Server (NTRS)

    Stegman, Thomas W.

    1992-01-01

    Ferrofluidic device indicates point of highest magnetic-flux density in workspace. Consists of bubble of ferrofluid in immiscible liquid carrier in clear plastic case. Used in flat block or tube. Axes of centering circle on flat-block version used to mark location of maximum flux density when bubble in circle. Device used to find point on wall corresponding to known point on opposite side of wall.

  9. Ammonia Leak Locator Study

    NASA Technical Reports Server (NTRS)

    Dodge, Franklin T.; Wuest, Martin P.; Deffenbaugh, Danny M.

    1995-01-01

    The thermal control system of International Space Station Alpha will use liquid ammonia as the heat exchange fluid. It is expected that small leaks (of the order perhaps of one pound of ammonia per day) may develop in the lines transporting the ammonia to the various facilities as well as in the heat exchange equipment. Such leaks must be detected and located before the supply of ammonia becomes critically low. For that reason, NASA-JSC has a program underway to evaluate instruments that can detect and locate ultra-small concentrations of ammonia in a high vacuum environment. To be useful, the instrument must be portable and small enough that an astronaut can easily handle it during extravehicular activity. An additional complication in the design of the instrument is that the environment immediately surrounding ISSA will contain small concentrations of many other gases from venting of onboard experiments as well as from other kinds of leaks. These other vapors include water, cabin air, CO2, CO, argon, N2, and ethylene glycol. Altogether, this local environment might have a pressure of the order of 10(exp -7) to 10(exp -6) torr. Southwest Research Institute (SwRI) was contracted by NASA-JSC to provide support to NASA-JSC and its prime contractors in evaluating ammonia-location instruments and to make a preliminary trade study of the advantages and limitations of potential instruments. The present effort builds upon an earlier SwRI study to evaluate ammonia leak detection instruments [Jolly and Deffenbaugh]. The objectives of the present effort include: (1) Estimate the characteristics of representative ammonia leaks; (2) Evaluate the baseline instrument in the light of the estimated ammonia leak characteristics; (3) Propose alternative instrument concepts; and (4) Conduct a trade study of the proposed alternative concepts and recommend promising instruments. The baseline leak-location instrument selected by NASA-JSC was an ion gauge.

  10. Machine tool locator

    DOEpatents

    Hanlon, John A.; Gill, Timothy J.

    2001-01-01

    Machine tools can be accurately measured and positioned on manufacturing machines within very small tolerances by use of an autocollimator on a 3-axis mount on a manufacturing machine and positioned so as to focus on a reference tooling ball or a machine tool, a digital camera connected to the viewing end of the autocollimator, and a marker and measure generator for receiving digital images from the camera, then displaying or measuring distances between the projection reticle and the reference reticle on the monitoring screen, and relating the distances to the actual position of the autocollimator relative to the reference tooling ball. The images and measurements are used to set the position of the machine tool and to measure the size and shape of the machine tool tip, and examine cutting edge wear. patent

  11. Location capability of a sparse regional network (RSTN) using a multi-phase earthquake location algorithm (REGLOC)

    SciTech Connect

    Hutchings, L.

    1994-01-01

    The Regional Seismic Test Network (RSTN) was deployed by the US Department of Energy (DOE) to determine whether data recorded by a regional network could be used to detect and accurately locate seismic events that might be clandestine nuclear tests. The purpose of this paper is to evaluate the location capability of the RSTN. A major part of this project was the development of the location algorithm REGLOC and application of Basian a prior statistics for determining the accuracy of the location estimates. REGLOC utilizes all identifiable phases, including backazimuth, in the location. Ninty-four events, distributed throughout the network area, detected by both the RSTN and located by local networks were used in the study. The location capability of the RSTN was evaluated by estimating the location accuracy, error ellipse accuracy, and the percentage of events that could be located, as a function of magnitude. The location accuracy was verified by comparing the RSTN results for the 94 events with published locations based on data from the local networks. The error ellipse accuracy was evaluated by determining whether the error ellipse includes the actual location. The percentage of events located was assessed by combining detection capability with location capability to determine the percentage of events that could be located within the study area. Events were located with both an average crustal model for the entire region, and with regional velocity models along with station corrections obtained from master events. Most events with a magnitude <3.0 can only be located with arrivals from one station. Their average location errors are 453 and 414 km for the average- and regional-velocity model locations, respectively. Single station locations are very unreliable because they depend on accurate backazimuth estimates, and backazimuth proved to be a very unreliable computation.

  12. Accurate adjoint design sensitivities for nano metal optics.

    PubMed

    Hansen, Paul; Hesselink, Lambertus

    2015-09-01

    We present a method for obtaining accurate numerical design sensitivities for metal-optical nanostructures. Adjoint design sensitivity analysis, long used in fluid mechanics and mechanical engineering for both optimization and structural analysis, is beginning to be used for nano-optics design, but it fails for sharp-cornered metal structures because the numerical error in electromagnetic simulations of metal structures is highest at sharp corners. These locations feature strong field enhancement and contribute strongly to design sensitivities. By using high-accuracy FEM calculations and rounding sharp features to a finite radius of curvature we obtain highly-accurate design sensitivities for 3D metal devices. To provide a bridge to the existing literature on adjoint methods in other fields, we derive the sensitivity equations for Maxwell's equations in the PDE framework widely used in fluid mechanics. PMID:26368483

  13. Mill profiler machines soft materials accurately

    NASA Technical Reports Server (NTRS)

    Rauschl, J. A.

    1966-01-01

    Mill profiler machines bevels, slots, and grooves in soft materials, such as styrofoam phenolic-filled cores, to any desired thickness. A single operator can accurately control cutting depths in contour or straight line work.

  14. Remote balance weighs accurately amid high radiation

    NASA Technical Reports Server (NTRS)

    Eggenberger, D. N.; Shuck, A. B.

    1969-01-01

    Commercial beam-type balance, modified and outfitted with electronic controls and digital readout, can be remotely controlled for use in high radiation environments. This allows accurate weighing of breeder-reactor fuel pieces when they are radioactively hot.

  15. Understanding the Code: keeping accurate records.

    PubMed

    Griffith, Richard

    2015-10-01

    In his continuing series looking at the legal and professional implications of the Nursing and Midwifery Council's revised Code of Conduct, Richard Griffith discusses the elements of accurate record keeping under Standard 10 of the Code. This article considers the importance of accurate record keeping for the safety of patients and protection of district nurses. The legal implications of records are explained along with how district nurses should write records to ensure these legal requirements are met. PMID:26418404

  16. Automated seismic event location by arrival time stacking: Applications to local and micro-seismicity

    NASA Astrophysics Data System (ADS)

    Grigoli, F.; Cesca, S.; Braun, T.; Philipp, J.; Dahm, T.

    2012-04-01

    Locating seismic events is one of the oldest problem in seismology. In microseismicity application, when the number of event is very large, it is not possible to locate earthquake manually and automated location procedures must be established. Automated seismic event location at different scales is very important in different application areas, including mining monitoring, reservoir geophysics and early warning systems. Location is needed to start rescue operations rapidly. Locating and mapping microearthquakes or acoustic emission sources in mining environments is important for monitoring of mines stability. Mapping fractures through microseimicity distribution inside hydrocarbon reservoirs is needed to find areas with an higher permeability and enhance oil production. In the last 20 years a large number of picking algorithm was developed in order to locate seismic events automatically. While P onsets can now be accurately picked using automatic routines, the automatic picking of later seismic phases (including S onset) is still problematic , thus limiting the location performance. In this work we present a picking free location method based on the use of the Short-Term-Average/Long-Term-Average (STA/LTA) traces at different stations as observed data. For different locations and origin times, observed STA/LTA are stacked along the travel time surface corresponding to the selected hypocentre. Iterating this procedure on a three-dimensional grid we retrieve a multidimensional matrix whose absolute maximum corresponds to the spatio-temporal coordinates of the seismic event. We tested our methodology on synthetic data, simulating different environments and network geometries. Finally, we apply our method to real datasets related to microseismic activity in mines and earthquake swarms in Italy. This work has been funded by the German BMBF "Geotechnologien" project MINE (BMBF03G0737A).

  17. Developmental aspects of memory for spatial location.

    PubMed

    Ellis, N R; Katz, E; Williams, J E

    1987-12-01

    The purpose was to show whether or not the encoding of location met criteria defining an automatic process (L. Hasher & R. T. Zacks, 1979, Journal of Experimental Psychology: General, 108, 356-388; 1984, American Psychologist, 39, 1372-1388). Among other criteria, automatic processes are not expected to show developmental changes beyond an early age, to be unrelated to intelligence level, and to be unaffected by instructions. In the first experiment preschool through sixth-grade children were compared on a 40-picturebook task following incidental (remember the names of pictures) or intentional (remember location) instruction. Subjects viewed and named pictures in sets of four, arranged in quadrants in the opened book, and then attempted to recall names of the objects pictured and to relocate pictures on blank pages. In the second experiment, second and sixth graders, college students, elderly persons, and mentally retarded persons were compared on a 60-picturebook task following either incidental or semantic incidental instructions (give the function of objects pictured). Memory for location was invariant across age groups and intelligence level. The only exception was that 3 and 4 year olds were more accurate following intentional instructions. Otherwise there were no differences between intentional and incidental instructions. Semantic instructions resulted in slightly more accurate locations. The results were interpreted as supportive of the Hasher and Zacks' automaticity hypothesis. PMID:3694123

  18. Sonar Locator Systems

    NASA Technical Reports Server (NTRS)

    1985-01-01

    An underwater locator device called a Pinger is attached to an airplane's flight recorder for recovery in case of a crash. Burnett Electronics Pinger Model 512 resulted from a Burnett Electronics Laboratory, Inc./Langley Research Center contract for development of a search system for underwater mines. The Pinger's battery-powered transmitter is activated when immersed in water, and sends multidirectional signals for up to 500 hours. When a surface receiver picks up the signal, a diver can retrieve the pinger and the attached airplane flight recorder. Other pingers are used to track whales, mark underwater discoveries and assist oil drilling vessels.

  19. Location of Planet X

    SciTech Connect

    Harrington, R.S.

    1988-10-01

    Observed positions of Uranus and Neptune along with residuals in right ascension and declination are used to constrain the location of a postulated tenth planet. The residuals are converted into residuals in ecliptic longitude and latitude. The results are then combined into seasonal normal points, producing average geocentric residuals spaced slightly more than a year apart that are assumed to represent the equivalent heliocentric average residuals for the observed oppositions. Such a planet is found to most likely reside in the region of Scorpius, with considerably less likelihood that it is in Taurus. 8 references.

  20. IncM Plasmid R1215 Is the Source of Chromosomally Located Regions Containing Multiple Antibiotic Resistance Genes in the Globally Disseminated Acinetobacter baumannii GC1 and GC2 Clones

    PubMed Central

    Blackwell, Grace A.

    2016-01-01

    ABSTRACT Clear similarities between antibiotic resistance islands in the chromosomes of extensively antibiotic-resistant isolates from the two dominant, globally distributed Acinetobacter baumannii clones, GC1 and GC2, suggest a common origin. A close relative of the likely progenitor of both of these regions was found in R1215, a conjugative IncM plasmid from a Serratia marcescens strain isolated prior to 1980. The 37.8-kb resistance region in R1215 lies within the mucB gene and includes aacC1, aadA1, aphA1b, blaTEM, catA1, sul1, and tetA(A), genes that confer resistance to gentamicin, streptomycin and spectinomycin, kanamycin and neomycin, ampicillin, chloramphenicol, sulfamethoxazole, and tetracycline, respectively. The backbone of this region is derived from Tn1721 and is interrupted by a hybrid Tn2670 (Tn21)-Tn1696-type transposon, Tn6020, and an incomplete Tn1. After minor rearrangements, this R1215 resistance island can generate AbGRI2-0*, the predicted earliest form of the IS26-bounded AbGRI2-type resistance island of GC2 isolates, and to the multiple antibiotic resistance region (MARR) of AbaR0, the precursor of this region in AbaR-type resistance islands in the GC1 group. A 29.9-kb circle excised by IS26 has been inserted into the A. baumannii chromosome to generate AbGRI2-0*. To create the MARR of AbaR0, a different circular form, again generated by IS26 from an R1215 resistance region variant, has been opened at a different point by recombination with a copy of the sul1 gene already present in the AbaR precursor. Recent IncM plasmids related to R1215 have a variant resistance island containing a blaSHV gene in the same location. IMPORTANCE Two lineages of extensively antibiotic-resistant A. baumannii currently plaguing modern medicine each acquired resistance to all of the original antibiotics (ampicillin, tetracycline, kanamycin, and sulfonamides) by the end of the 1970s and then became resistant to antibiotics from newer families after they were

  1. IncM Plasmid R1215 Is the Source of Chromosomally Located Regions Containing Multiple Antibiotic Resistance Genes in the Globally Disseminated Acinetobacter baumannii GC1 and GC2 Clones.

    PubMed

    Blackwell, Grace A; Hamidian, Mohammad; Hall, Ruth M

    2016-01-01

    Clear similarities between antibiotic resistance islands in the chromosomes of extensively antibiotic-resistant isolates from the two dominant, globally distributed Acinetobacter baumannii clones, GC1 and GC2, suggest a common origin. A close relative of the likely progenitor of both of these regions was found in R1215, a conjugative IncM plasmid from a Serratia marcescens strain isolated prior to 1980. The 37.8-kb resistance region in R1215 lies within the mucB gene and includes aacC1, aadA1, aphA1b, bla TEM, catA1, sul1, and tetA(A), genes that confer resistance to gentamicin, streptomycin and spectinomycin, kanamycin and neomycin, ampicillin, chloramphenicol, sulfamethoxazole, and tetracycline, respectively. The backbone of this region is derived from Tn1721 and is interrupted by a hybrid Tn2670 (Tn21)-Tn1696-type transposon, Tn6020, and an incomplete Tn1. After minor rearrangements, this R1215 resistance island can generate AbGRI2-0*, the predicted earliest form of the IS26-bounded AbGRI2-type resistance island of GC2 isolates, and to the multiple antibiotic resistance region (MARR) of AbaR0, the precursor of this region in AbaR-type resistance islands in the GC1 group. A 29.9-kb circle excised by IS26 has been inserted into the A. baumannii chromosome to generate AbGRI2-0*. To create the MARR of AbaR0, a different circular form, again generated by IS26 from an R1215 resistance region variant, has been opened at a different point by recombination with a copy of the sul1 gene already present in the AbaR precursor. Recent IncM plasmids related to R1215 have a variant resistance island containing a bla SHV gene in the same location. IMPORTANCE Two lineages of extensively antibiotic-resistant A. baumannii currently plaguing modern medicine each acquired resistance to all of the original antibiotics (ampicillin, tetracycline, kanamycin, and sulfonamides) by the end of the 1970s and then became resistant to antibiotics from newer families after they were introduced

  2. Semantic Location Extraction from Crowdsourced Data

    NASA Astrophysics Data System (ADS)

    Koswatte, S.; Mcdougall, K.; Liu, X.

    2016-06-01

    Crowdsourced Data (CSD) has recently received increased attention in many application areas including disaster management. Convenience of production and use, data currency and abundancy are some of the key reasons for attracting this high interest. Conversely, quality issues like incompleteness, credibility and relevancy prevent the direct use of such data in important applications like disaster management. Moreover, location information availability of CSD is problematic as it remains very low in many crowd sourced platforms such as Twitter. Also, this recorded location is mostly related to the mobile device or user location and often does not represent the event location. In CSD, event location is discussed descriptively in the comments in addition to the recorded location (which is generated by means of mobile device's GPS or mobile communication network). This study attempts to semantically extract the CSD location information with the help of an ontological Gazetteer and other available resources. 2011 Queensland flood tweets and Ushahidi Crowd Map data were semantically analysed to extract the location information with the support of Queensland Gazetteer which is converted to an ontological gazetteer and a global gazetteer. Some preliminary results show that the use of ontologies and semantics can improve the accuracy of place name identification of CSD and the process of location information extraction.

  3. Examining the spatial congruence between data obtained with a novel activity location questionnaire, continuous GPS tracking, and prompted recall surveys

    PubMed Central

    2013-01-01

    Background Place and health researchers are increasingly interested in integrating individuals’ mobility and the experience they have with multiple settings in their studies. In practice, however, few tools exist which allow for rapid and accurate gathering of detailed information on the geographic location of places where people regularly undertake activities. We describe the development and validation of a new activity location questionnaire which can be useful in accounting for multiple environmental influences in large population health investigations. Methods To develop the questionnaire, we relied on a literature review of similar data collection tools and on results of a pilot study wherein we explored content validity, test-retest reliability, and face validity. To estimate convergent validity, we used data from a study of users of a public bicycle share program conducted in Montreal, Canada in 2011. We examined the spatial congruence between questionnaire data and data from three other sources: 1) one-week GPS tracks; 2) activity locations extracted from the GPS tracks; and 3) a prompted recall survey of locations visited during the day. Proximity and convex hull measures were used to compare questionnaire-derived data and GPS and prompted recall survey data. Results In the sample, 75% of questionnaire-reported activity locations were located within 400 meters of an activity location recorded on the GPS track or through the prompted recall survey. Results from convex hull analyses suggested questionnaire activity locations were more concentrated in space than GPS or prompted-recall locations. Conclusions The new questionnaire has high convergent validity and can be used to accurately collect data on regular activity spaces in terms of locations regularly visited. The methods, measures, and findings presented provide new material to further study mobility in place and health research. PMID:24025119

  4. [Electronic Apex Locator as a dental instrument].

    PubMed

    Lin, S; Winocur-Arias, O; Slutzky-Goldberg, I

    2009-04-01

    Electronic Apex Locators (EAL) have become widely used in the last decade. The first apex locator was introduced in 1962, based on a constant electrical resistance (6.5 K.) between the oral mucosa and periodontal ligament. The first and second generations of EAL were inaccurate and could not detect the apex in the presence of conducting fluids. The third generation solved this problem by using two alternating frequencies and calculating the impedance between them. This provided reliable and accurate results in dry canals, or in the presence of blood, electrolytes or other fluid in the root canals, when the pulp was necrotic or when there was a perforation along the root. The Root ZX and Apit (Endex) are the most documented devices. The new fourth generation of apex locators is a diverse group: some use multifrequency currents, others use a "lookup matrix" rather than calculate the readings. Several of the newer EALs are smaller, and others connect to computers. PMID:20162984

  5. Accurately Determining the Risks of Rising Sea Level

    NASA Astrophysics Data System (ADS)

    Marbaix, Philippe; Nicholls, Robert J.

    2007-10-01

    With the highest density of people and the greatest concentration of economic activity located in the coastal regions, sea level rise is an important concern as the climate continues to warm. Subsequent flooding may potentially disrupt industries, populations, and livelihoods, particularly in the long term if the climate is not quickly stabilized [McGranahan et al., 2007; Tol et al., 2006]. To help policy makers understand these risks, a more accurate description of hazards posed by rising sea levels is needed at the global scale, even though the impacts in specific regions are better known.

  6. Calibration Techniques for Accurate Measurements by Underwater Camera Systems.

    PubMed

    Shortis, Mark

    2015-01-01

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems. PMID:26690172

  7. Calibration Techniques for Accurate Measurements by Underwater Camera Systems

    PubMed Central

    Shortis, Mark

    2015-01-01

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems. PMID:26690172

  8. Detection, localization and classification of multiple dipole-like magnetic sources using magnetic gradient tensor data

    NASA Astrophysics Data System (ADS)

    Gang, Yin; Yingtang, Zhang; Hongbo, Fan; Zhining, Li; Guoquan, Ren

    2016-05-01

    We have developed a method for automatic detection, localization and classification (DLC) of multiple dipole sources using magnetic gradient tensor data. First, we define modified tilt angles to estimate the approximate horizontal locations of the multiple dipole-like magnetic sources simultaneously and detect the number of magnetic sources using a fixed threshold. Secondly, based on the isotropy of the normalized source strength (NSS) response of a dipole, we obtain accurate horizontal locations of the dipoles. Then the vertical locations are calculated using magnitude magnetic transforms of magnetic gradient tensor data. Finally, we invert for the magnetic moments of the sources using the measured magnetic gradient tensor data and forward model. Synthetic and field data sets demonstrate effectiveness and practicality of the proposed method.

  9. Acoustic wave-equation-based earthquake location

    NASA Astrophysics Data System (ADS)

    Tong, Ping; Yang, Dinghui; Liu, Qinya; Yang, Xu; Harris, Jerry

    2016-04-01

    We present a novel earthquake location method using acoustic wave-equation-based traveltime inversion. The linear relationship between the location perturbation (δt0, δxs) and the resulting traveltime residual δt of a particular seismic phase, represented by the traveltime sensitivity kernel K(t0, xs) with respect to the earthquake location (t0, xs), is theoretically derived based on the adjoint method. Traveltime sensitivity kernel K(t0, xs) is formulated as a convolution between the forward and adjoint wavefields, which are calculated by numerically solving two acoustic wave equations. The advantage of this newly derived traveltime kernel is that it not only takes into account the earthquake-receiver geometry but also accurately honours the complexity of the velocity model. The earthquake location is obtained by solving a regularized least-squares problem. In 3-D realistic applications, it is computationally expensive to conduct full wave simulations. Therefore, we propose a 2.5-D approach which assumes the forward and adjoint wave simulations within a 2-D vertical plane passing through the earthquake and receiver. Various synthetic examples show the accuracy of this acoustic wave-equation-based earthquake location method. The accuracy and efficiency of the 2.5-D approach for 3-D earthquake location are further verified by its application to the 2004 Big Bear earthquake in Southern California.

  10. Geolocating Russian sources for Arctic black carbon

    NASA Astrophysics Data System (ADS)

    Cheng, Meng-Dawn

    2014-08-01

    To design and implement an effective emission control strategy for black carbon (BC), the locations and strength of BC sources must be identified. Lack of accurate source information from the Russian Federation has created difficulty for a range of research and policy activities in the Arctic because Russia occupies the largest landmass in the Arctic Circle. A project was initiated to resolve emission sources of BC in the Russian Federation by using the Potential Source Contribution Function (PSCF). It used atmospheric BC data from two Arctic sampling stations at Alert Nunavut, Canada, and Tiksi Bay, Russia. The geographical regions of BC emission sources in Russia were identified and summarized as follows: (1) a region surrounding Moscow, (2) regions in Eurasia stretching along the Ural Mountains from the White Sea to the Black Sea, and (3) a number of scattered areas from western Siberia to the Russian Far East. Particulate potassium ions, non-marine sulfate, and vanadium were used to assist in resolving the source types: forest fire/biomass burning, coal-fired power plant, and oil combustion. Correlating these maps with the BC map helped to resolve source regions of BC emissions and connect them to their corresponding source types. The results imply that a region south of Moscow and another north of the Ural Mountains could be significant BC sources, but none of the grid cells in these regions could be linked to forest fires, oil combustion, or coal-fired power plants based on these three markers.

  11. Groth Deep Locations Image

    NASA Technical Reports Server (NTRS)

    2003-01-01

    NASA's Galaxy Evolution Explorer photographed this ultraviolet color blowup of the Groth Deep Image on June 22 and June 23, 2003. Hundreds of galaxies are detected in this portion of the image, and the faint red galaxies are believed to be 6 billion light years away. The white boxes show the location of these distant galaxies, of which more than a 100 can be detected in this image. NASA astronomers expect to detect 10,000 such galaxies after extrapolating to the full image at a deeper exposure level.

    The Galaxy Evolution Explorer mission is led by the California Institute of Technology, which is also responsible for the science operations and data analysis. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of Caltech, manages the mission and built the science instrument. The mission was developed under NASA's Explorers Program, managed by the Goddard Space Flight Center, Greenbelt, Md. The mission's international partners include South Korea and France.

  12. Fixed-Wing Micro Aerial Vehicle for Accurate Corridor Mapping

    NASA Astrophysics Data System (ADS)

    Rehak, M.; Skaloud, J.

    2015-08-01

    In this study we present a Micro Aerial Vehicle (MAV) equipped with precise position and attitude sensors that together with a pre-calibrated camera enables accurate corridor mapping. The design of the platform is based on widely available model components to which we integrate an open-source autopilot, customized mass-market camera and navigation sensors. We adapt the concepts of system calibration from larger mapping platforms to MAV and evaluate them practically for their achievable accuracy. We present case studies for accurate mapping without ground control points: first for a block configuration, later for a narrow corridor. We evaluate the mapping accuracy with respect to checkpoints and digital terrain model. We show that while it is possible to achieve pixel (3-5 cm) mapping accuracy in both cases, precise aerial position control is sufficient for block configuration, the precise position and attitude control is required for corridor mapping.

  13. Multimodal Spatial Calibration for Accurately Registering EEG Sensor Positions

    PubMed Central

    Chen, Shengyong; Xiao, Gang; Li, Xiaoli

    2014-01-01

    This paper proposes a fast and accurate calibration method to calibrate multiple multimodal sensors using a novel photogrammetry system for fast localization of EEG sensors. The EEG sensors are placed on human head and multimodal sensors are installed around the head to simultaneously obtain all EEG sensor positions. A multiple views' calibration process is implemented to obtain the transformations of multiple views. We first develop an efficient local repair algorithm to improve the depth map, and then a special calibration body is designed. Based on them, accurate and robust calibration results can be achieved. We evaluate the proposed method by corners of a chessboard calibration plate. Experimental results demonstrate that the proposed method can achieve good performance, which can be further applied to EEG source localization applications on human brain. PMID:24803954

  14. Method for Accurately Calibrating a Spectrometer Using Broadband Light

    NASA Technical Reports Server (NTRS)

    Simmons, Stephen; Youngquist, Robert

    2011-01-01

    A novel method has been developed for performing very fine calibration of a spectrometer. This process is particularly useful for modern miniature charge-coupled device (CCD) spectrometers where a typical factory wavelength calibration has been performed and a finer, more accurate calibration is desired. Typically, the factory calibration is done with a spectral line source that generates light at known wavelengths, allowing specific pixels in the CCD array to be assigned wavelength values. This method is good to about 1 nm across the spectrometer s wavelength range. This new method appears to be accurate to about 0.1 nm, a factor of ten improvement. White light is passed through an unbalanced Michelson interferometer, producing an optical signal with significant spectral variation. A simple theory can be developed to describe this spectral pattern, so by comparing the actual spectrometer output against this predicted pattern, errors in the wavelength assignment made by the spectrometer can be determined.

  15. Multimodal spatial calibration for accurately registering EEG sensor positions.

    PubMed

    Zhang, Jianhua; Chen, Jian; Chen, Shengyong; Xiao, Gang; Li, Xiaoli

    2014-01-01

    This paper proposes a fast and accurate calibration method to calibrate multiple multimodal sensors using a novel photogrammetry system for fast localization of EEG sensors. The EEG sensors are placed on human head and multimodal sensors are installed around the head to simultaneously obtain all EEG sensor positions. A multiple views' calibration process is implemented to obtain the transformations of multiple views. We first develop an efficient local repair algorithm to improve the depth map, and then a special calibration body is designed. Based on them, accurate and robust calibration results can be achieved. We evaluate the proposed method by corners of a chessboard calibration plate. Experimental results demonstrate that the proposed method can achieve good performance, which can be further applied to EEG source localization applications on human brain. PMID:24803954

  16. Reconstructing spatially extended brain sources via enforcing multiple transform sparseness.

    PubMed

    Zhu, Min; Zhang, Wenbo; Dickens, Deanna L; Ding, Lei

    2014-02-01

    Accurate estimation of location and extent of neuronal sources from EEG/MEG remain challenging. In the present study, a new source imaging method, i.e. variation and wavelet based sparse source imaging (VW-SSI), is proposed to better estimate cortical source locations and extents. VW-SSI utilizes the L1-norm regularization method with the enforcement of transform sparseness in both variation and wavelet domains. The performance of the proposed method is assessed by both simulated and experimental MEG data, obtained from a language task and a motor task. Compared to L2-norm regularizations, VW-SSI demonstrates significantly improved capability in reconstructing multiple extended cortical sources with less spatial blurredness and less localization error. With the use of transform sparseness, VW-SSI overcomes the over-focused problem in classic SSI methods. With the use of two transformations, VW-SSI further indicates significantly better performance in estimating MEG source locations and extents than other SSI methods with single transformations. The present experimental results indicate that VW-SSI can successfully estimate neural sources (and their spatial coverage) located in close areas while responsible for different functions, i.e. temporal cortical sources for auditory and language processing, and sources on the pre-bank and post-bank of the central sulcus. Meantime, all other methods investigated in the present study fail to recover these phenomena. Precise estimation of cortical source locations and extents from EEG/MEG is of significance for applications in neuroscience and neurology. PMID:24103850

  17. Efficient Location of Information in Special Education.

    ERIC Educational Resources Information Center

    Kissinger, Patricia; Ary, Donald

    Many individuals are concerned that the "knowledge explosion" in special education is making it difficult to keep up with research in the field. However, at the same time that knowledge has been expanding, efficient ways of locating knowledge have developed and additional sources of integrative reviews of research have appeared. The paper…

  18. Station Correction Uncertainty in Multiple Event Location Algorithms and the Effect on Error Ellipses

    SciTech Connect

    Erickson, Jason P.; Carlson, Deborah K.; Ortiz, Anne; Hutchenson, Kevin; Oweisny, Linda; Kraft, Gordon; Anderson, Dale N.; Tinker, Mark

    2003-10-30

    Accurate location of seismic events is crucial for nuclear explosion monitoring. There are several sources of error in seismic location that must be taken into account to obtain high confidence results. Most location techniques account for uncertainties in the phase arrival times (measurement error) and the bias of the velocity model (model error), but they do not account for the uncertainty of the velocity model bias. By determining and incorporating this uncertainty in the location algorithm we seek to improve the accuracy of the calculated locations and uncertainty ellipses. In order to correct for deficiencies in the velocity model, it is necessary to apply station specific corrections to the predicted arrival times. Both master event and multiple event location techniques assume that the station corrections are known perfectly, when in reality there is an uncertainty associated with these corrections. For multiple event location algorithms that calculate station corrections as part of the inversion, it is possible to determine the variance of the corrections. The variance can then be used to weight the arrivals associated with each station, thereby giving more influence to stations with consistent corrections. We have modified an existing multiple event location program (based on PMEL, Pavlis and Booker, 1983). We are exploring weighting arrivals with the inverse of the station correction standard deviation as well using the conditional probability of the calculated station corrections. This is in addition to the weighting already given to the measurement and modeling error terms. We re-locate a group of mining explosions that occurred at Black Thunder, Wyoming, and compare the results to those generated without accounting for station correction uncertainty.

  19. Locating Patient Expertise in Everyday Life

    PubMed Central

    Civan, Andrea; McDonald, David W.; Unruh, Kenton T.; Pratt, Wanda

    2010-01-01

    Coping with a new health issue often requires individuals to acquire knowledge and skills to manage personal health. Many patients turn to one another for experiential expertise outside the formal bounds of the health-care system. Internet-based social software can facilitate expertise sharing among patients, but provides only limited ways for users to locate sources of patient expertise. Although much prior research has investigated expertise location and systems to augment expertise sharing in workplace organizations, the transferability of this knowledge to other contexts, such as personal health, is unclear. Guided by expertise locating frameworks drawn from prior work, we conducted a field study to investigate expertise locating in the informal and everyday context of women diagnosed with breast cancer. Similarities between patients’ expertise locating practices and practices of professionals in workplace organizations suggest similar support strategies could apply in both contexts. However, unlike professionals, unsolicited advice often triggered patients to locate expertise. They identified expertise through various forms of gatekeeping. The high-stakes nature of problems patients faced also led them to use triangulation strategies in anticipation of breakdowns in expertise location. Based on these key differences, we explored five design additions to social software that could support patients in their critical need to locate patient expertise. PMID:20953244

  20. A highly accurate interatomic potential for argon

    NASA Astrophysics Data System (ADS)

    Aziz, Ronald A.

    1993-09-01

    A modified potential based on the individually damped model of Douketis, Scoles, Marchetti, Zen, and Thakkar [J. Chem. Phys. 76, 3057 (1982)] is presented which fits, within experimental error, the accurate ultraviolet (UV) vibration-rotation spectrum of argon determined by UV laser absorption spectroscopy by Herman, LaRocque, and Stoicheff [J. Chem. Phys. 89, 4535 (1988)]. Other literature potentials fail to do so. The potential also is shown to predict a large number of other properties and is probably the most accurate characterization of the argon interaction constructed to date.

  1. Accurate and Precise Zinc Isotope Ratio Measurements in Urban Aerosols

    NASA Astrophysics Data System (ADS)

    Weiss, D.; Gioia, S. M. C. L.; Coles, B.; Arnold, T.; Babinski, M.

    2009-04-01

    We developed an analytical method and constrained procedural boundary conditions that enable accurate and precise Zn isotope ratio measurements in urban aerosols. We also demonstrate the potential of this new isotope system for air pollutant source tracing. The procedural blank is around 5 ng and significantly lower than published methods due to a tailored ion chromatographic separation. Accurate mass bias correction using external correction with Cu is limited to Zn sample content of approximately 50 ng due to the combined effect of blank contribution of Cu and Zn from the ion exchange procedure and the need to maintain a Cu/Zn ratio of approximately 1. Mass bias is corrected for by applying the common analyte internal standardization method approach. Comparison with other mass bias correction methods demonstrates the accuracy of the method. The average precision of δ66Zn determinations in aerosols is around 0.05 per mil per atomic mass unit. The method was tested on aerosols collected in Sao Paulo City, Brazil. The measurements reveal significant variations in δ66Zn ranging between -0.96 and -0.37 per mil in coarse and between -1.04 and 0.02 per mil in fine particular matter. This variability suggests that Zn isotopic compositions distinguish atmospheric sources. The isotopic light signature suggests traffic as the main source.

  2. Location of Microearthquakes in Various Noisy Environments Using Envelope Stacking

    NASA Astrophysics Data System (ADS)

    Oye, V.; Gharti, H.

    2009-12-01

    Monitoring of microearthquakes is routinely conducted in various environments such as hydrocarbon and geothermal reservoirs, mines, dams, seismically active faults, volcanoes, nuclear power plants and CO2 storages. In many of these cases the handled data is sensitive and the interpretation of the data may be vital. In some cases, such as during mining or hydraulic fracturing activities, the number of microearthquakes is very large with tens to thousands of events per hour. In others, almost no events occur during a week and furthermore, it might not be anticipated that many events occur at all. However, the general setup of seismic networks, including surface and downhole stations, is usually optimized to record as many microearthquakes as possible, thereby trying to lower the detection threshold of the network. This process is obviously limited to some extent. Most microearthquake location techniques take advantage of a combination of P- and S-wave onset times that often can be picked reliably in an automatic mode. Moreover, when using seismic wave onset times, sometimes in combination with seismic wave polarization, these methods are more accurate compared to migration-based location routines. However, many events cannot be located because their magnitude is too small, i.e. the P- and/or S-wave onset times cannot be picked accurately on a sufficient number of receivers. Nevertheless, these small events are important for the interpretation of the processes that are monitored and even an inferior estimate of event locations and strengths is valuable information. Moreover, the smaller the event the more often such events statistically occur and the more important such additional information becomes. In this study we try to enhance the performance of any microseismic network, providing additional estimates of event locations below the actual detection threshold. We present a migration-based event location method, where we project the recorded seismograms onto the ray

  3. Close binding of identity and location in visual feature perception

    NASA Technical Reports Server (NTRS)

    Johnston, J. C.; Pashler, H.

    1990-01-01

    The binding of identity and location information in disjunctive feature search was studied. Ss searched a heterogeneous display for a color or a form target, and reported both target identity and location. To avoid better than chance guessing of target identity (by choosing the target less likely to have been seen), the difficulty of the two targets was equalized adaptively; a mathematical model was used to quantify residual effects. A spatial layout was used that minimized postperceptual errors in reporting location. Results showed strong binding of identity and location perception. After correction for guessing, no perception of identity without location was found. A weak trend was found for accurate perception of target location without identity. We propose that activated features generate attention-calling "interrupt" signals, specifying only location; attention then retrieves the properties at that location.

  4. Method and apparatus for accurately manipulating an object during microelectrophoresis

    DOEpatents

    Parvin, Bahram A.; Maestre, Marcos F.; Fish, Richard H.; Johnston, William E.

    1997-01-01

    An apparatus using electrophoresis provides accurate manipulation of an object on a microscope stage for further manipulations add reactions. The present invention also provides an inexpensive and easily accessible means to move an object without damage to the object. A plurality of electrodes are coupled to the stage in an array whereby the electrode array allows for distinct manipulations of the electric field for accurate manipulations of the object. There is an electrode array control coupled to the plurality of electrodes for manipulating the electric field. In an alternative embodiment, a chamber is provided on the stage to hold the object. The plurality of electrodes are positioned in the chamber, and the chamber is filled with fluid. The system can be automated using visual servoing, which manipulates the control parameters, i.e., x, y stage, applying the field, etc., after extracting the significant features directly from image data. Visual servoing includes an imaging device and computer system to determine the location of the object. A second stage having a plurality of tubes positioned on top of the second stage, can be accurately positioned by visual servoing so that one end of one of the plurality of tubes surrounds at least part of the object on the first stage.

  5. Method and apparatus for accurately manipulating an object during microelectrophoresis

    DOEpatents

    Parvin, B.A.; Maestre, M.F.; Fish, R.H.; Johnston, W.E.

    1997-09-23

    An apparatus using electrophoresis provides accurate manipulation of an object on a microscope stage for further manipulations and reactions. The present invention also provides an inexpensive and easily accessible means to move an object without damage to the object. A plurality of electrodes are coupled to the stage in an array whereby the electrode array allows for distinct manipulations of the electric field for accurate manipulations of the object. There is an electrode array control coupled to the plurality of electrodes for manipulating the electric field. In an alternative embodiment, a chamber is provided on the stage to hold the object. The plurality of electrodes are positioned in the chamber, and the chamber is filled with fluid. The system can be automated using visual servoing, which manipulates the control parameters, i.e., x, y stage, applying the field, etc., after extracting the significant features directly from image data. Visual servoing includes an imaging device and computer system to determine the location of the object. A second stage having a plurality of tubes positioned on top of the second stage, can be accurately positioned by visual servoing so that one end of one of the plurality of tubes surrounds at least part of the object on the first stage. 11 figs.

  6. Atom location by electron channeling analysis

    SciTech Connect

    Pennycook, S.J.

    1984-07-01

    For many years the orientation dependence of the characteristic x-ray emission close to a Bragg reflection has been regarded as a hindrance to accurate microanalysis, and a random incident beam direction has always been recommended for accurate composition analysis. However, this orientation dependence can be put to use to extract information on the lattice location of foreign atoms within the crystalline matrix. Here a generalization of the technique is described which is applicable to any crystal structure including monatomic crystals, and can quantitatively determine substitutional fractions of impurities. The technique was referred to as electron channeling analysis, by analogy with the closely related and widely used bulk technique of ion channeling analysis, and was developed for lattice location studies of dopants in semiconductors at high spatial resolution. Only two spectra are required for each channeling analysis, one in each of the channeling conditions described above. If the matrix and dopant x-ray yields vary identically between the two orientations then the dopant necessarily lies within the reflecting matrix planes. If the dopant x-ray yield does not vary the dopant atoms are randomly located with respect to the matrix planes. 10 references, 2 figures.

  7. Object Locating System

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Carl, James R. (Inventor)

    2000-01-01

    A portable system is provided that is operational for determining, with three dimensional resolution, the position of a buried object or approximately positioned object that may move in space or air or gas. The system has a plurality of receivers for detecting the signal front a target antenna and measuring the phase thereof with respect to a reference signal. The relative permittivity and conductivity of the medium in which the object is located is used along with the measured phase signal to determine a distance between the object and each of the plurality of receivers. Knowing these distances. an iteration technique is provided for solving equations simultaneously to provide position coordinates. The system may also be used for tracking movement of an object within close range of the system by sampling and recording subsequent position of the object. A dipole target antenna. when positioned adjacent to a buried object, may be energized using a separate transmitter which couples energy to the target antenna through the medium. The target antenna then preferably resonates at a different frequency, such as a second harmonic of the transmitter frequency.

  8. Submerged marine streamer locator

    SciTech Connect

    Roberts, F.A.

    1987-01-06

    An apparatus is described for use in determining relative to known geographic locations on a sea floor the position of a moving submerged marine seismic streamer while being towed through the sea by an exploration vessel, which comprises: spaced apart acoustic receivers and at least one acoustic transducer-receiver carried by the streamer. The transducer-receiver is capable of emitting acoustic command signals when triggered by means controllable from the moving vessel and the receivers are capable of receiving and distinguishing distinctly different acoustic frequencies to transmit distinguishable signals responsive thereto along the streamer to recording means on the vessel; at least three sea floor transponders spatially displaced from each other at known positions relative to the sea floor and each of the transponders being capable of responding to a single acoustic command signal from the transducer-receiver in the moving streamer while being towed by the vessel. Each of the transponders emits signals of a distinctly different frequency; and means for recording the time interval from initiation of a command signal from the streamer transducer to the receipt of each signal relayed along the streamer from each of the receivers in response to the signals from the transponders. In this way, the distance of each of the streamer receivers from each of the known positions of the transponders may be calculated.

  9. AOTV bow shock location

    NASA Technical Reports Server (NTRS)

    Desautel, D.

    1985-01-01

    Hypersonic bow-shock location and geometry are of central importance to the aerodynamics and aerothermodynamics of aeroassisted orbital transfer vehicles (AOTVs), but they are difficult to predict for a given vehicle configuration. This paper reports experimental measurements of shock standoff distance for the 70 deg cone AOTV configuration in shock-tunnel-test flows at Mach numbers of 3.8 to 7.9 and for angles of attack from 0 deg to 20 deg. The controlling parameter for hypersonic bow-shock standoff distance (for a given forebody shape) is the mean normal-shock density ratio. Values for this parameter in the tests reported are in the same range as those of the drag-brake AOTV perigee regime. Results for standoff distance are compared with those previously reported in the literature for this AOTV configuration. It is concluded that the AOTV shock standoff distance for the conical configuration, based on frustrum (base) radius, is equivalent to that of a sphere with a radius about 35 percent greater than that of the cone; the distance is, therefore, much less than reported in previous studies. Some reasons for the discrepancies between the present and previous are advanced. The smaller standoff distance determined here implies there will be less radiative heat transfer than was previously expected.

  10. Accurate pointing of tungsten welding electrodes

    NASA Technical Reports Server (NTRS)

    Ziegelmeier, P.

    1971-01-01

    Thoriated-tungsten is pointed accurately and quickly by using sodium nitrite. Point produced is smooth and no effort is necessary to hold the tungsten rod concentric. The chemically produced point can be used several times longer than ground points. This method reduces time and cost of preparing tungsten electrodes.

  11. Development and Validation of a Multidisciplinary Tool for Accurate and Efficient Rotorcraft Noise Prediction (MUTE)

    NASA Technical Reports Server (NTRS)

    Liu, Yi; Anusonti-Inthra, Phuriwat; Diskin, Boris

    2011-01-01

    A physics-based, systematically coupled, multidisciplinary prediction tool (MUTE) for rotorcraft noise was developed and validated with a wide range of flight configurations and conditions. MUTE is an aggregation of multidisciplinary computational tools that accurately and efficiently model the physics of the source of rotorcraft noise, and predict the noise at far-field observer locations. It uses systematic coupling approaches among multiple disciplines including Computational Fluid Dynamics (CFD), Computational Structural Dynamics (CSD), and high fidelity acoustics. Within MUTE, advanced high-order CFD tools are used around the rotor blade to predict the transonic flow (shock wave) effects, which generate the high-speed impulsive noise. Predictions of the blade-vortex interaction noise in low speed flight are also improved by using the Particle Vortex Transport Method (PVTM), which preserves the wake flow details required for blade/wake and fuselage/wake interactions. The accuracy of the source noise prediction is further improved by utilizing a coupling approach between CFD and CSD, so that the effects of key structural dynamics, elastic blade deformations, and trim solutions are correctly represented in the analysis. The blade loading information and/or the flow field parameters around the rotor blade predicted by the CFD/CSD coupling approach are used to predict the acoustic signatures at far-field observer locations with a high-fidelity noise propagation code (WOPWOP3). The predicted results from the MUTE tool for rotor blade aerodynamic loading and far-field acoustic signatures are compared and validated with a variation of experimental data sets, such as UH60-A data, DNW test data and HART II test data.

  12. Assessing sensitivity of source term estimation

    NASA Astrophysics Data System (ADS)

    Long, Kerrie J.; Haupt, Sue Ellen; Young, George S.

    2010-04-01

    Source term estimation algorithms compute unknown atmospheric transport and dispersion modeling variables from concentration observations made by sensors in the field. Insufficient spatial and temporal resolution in the meteorological data as well as inherent uncertainty in the wind field data make source term estimation and the prediction of subsequent transport and dispersion extremely difficult. This work addresses the question: how many sensors are necessary in order to successfully estimate the source term and meteorological variables required for atmospheric transport and dispersion modeling? The source term estimation system presented here uses a robust optimization technique - a genetic algorithm (GA) - to find the combination of source location, source height, source strength, surface wind direction, surface wind speed, and time of release that produces a concentration field that best matches the sensor observations. The approach is validated using the Gaussian puff as the dispersion model in identical twin numerical experiments. The limits of the system are tested by incorporating additive and multiplicative noise into the synthetic data. The minimum requirements for data quantity and quality are determined by an extensive grid sensitivity analysis. Finally, a metric is developed for quantifying the minimum number of sensors necessary to accurately estimate the source term and to obtain the relevant wind information.

  13. Transfer of location-specific control to untrained locations.

    PubMed

    Weidler, Blaire J; Bugg, Julie M

    2016-11-01

    Recent research highlights a seemingly flexible and automatic form of cognitive control that is triggered by potent contextual cues, as exemplified by the location-specific proportion congruence effect--reduced compatibility effects in locations associated with a high as compared to low likelihood of conflict. We investigated just how flexible location-specific control is by examining whether novel locations effectively cue control for congruency-unbiased stimuli. In two experiments, biased (mostly compatible or mostly incompatible) training stimuli appeared in distinct locations. During a final block, unbiased (50% compatible) stimuli appeared in novel untrained locations spatially linked to biased locations. The flanker compatibly effect was reduced for unbiased stimuli in novel locations linked to a mostly incompatible compared to a mostly compatible location, indicating transfer. Transfer was observed when stimuli appeared along a linear function (Experiment 1) or in rings of a bullseye (Experiment 2). The novel transfer effects imply that location-specific control is more flexible than previously reported and further counter the complex stimulus-response learning account of location-specific proportion congruence effects. We propose that the representation and retrieval of control settings in untrained locations may depend on environmental support and the presentation of stimuli in novel locations that fall within the same categories of space as trained locations. PMID:26800157

  14. An accurate Rb density measurement method for a plasma wakefield accelerator experiment using a novel Rb reservoir

    NASA Astrophysics Data System (ADS)

    Öz, E.; Batsch, F.; Muggli, P.

    2016-09-01

    A method to accurately measure the density of Rb vapor is described. We plan on using this method for the Advanced Wakefield (AWAKE) (Assmann et al., 2014 [1]) project at CERN , which will be the world's first proton driven plasma wakefield experiment. The method is similar to the hook (Marlow, 1967 [2]) method and has been described in great detail in the work by Hill et al. (1986) [3]. In this method a cosine fit is applied to the interferogram to obtain a relative accuracy on the order of 1% for the vapor density-length product. A single-mode, fiber-based, Mach-Zenhder interferometer will be built and used near the ends of the 10 meter-long AWAKE plasma source to be able to make accurate relative density measurement between these two locations. This can then be used to infer the vapor density gradient along the AWAKE plasma source and also change it to the value desired for the plasma wakefield experiment. Here we describe the plan in detail and show preliminary results obtained using a prototype 8 cm long novel Rb vapor cell.

  15. Pioneer F Plaque Location

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The Pioneer F spacecraft, destined to be the first man made object to escape from the solar system into interstellar space, carries this pictorial plaque. It is designed to show scientifically educated inhabitants of some other star system, who might intercept it millions of years from now, when Pioneer was launched, from where, and by what kind of beings. (Hopefully, any aliens reading the plaque will not use this knowledge to immediately invade Earth.) The design is etched into a 6 inch by 9 inch gold-anodized aluminum plate, attached to the spacecraft's attenna support struts in a position to help shield it from erosion by interstellar dust. The radiating lines at left represents the positions of 14 pulsars, a cosmic source of radio energy, arranged to indicate our sun as the home star of our civilization. The '1-' symbols at the ends of the lines are binary numbers that represent the frequencies of these pulsars at the time of launch of Pioneer F relative of that to the hydrogen atom shown at the upper left with a '1' unity symbol. The hydrogen atom is thus used as a 'universal clock,' and the regular decrease in the frequencies of the pulsars will enable another civilization to determine the time that has elapsed since Pioneer F was launched. The hydrogen is also used as a 'universal yardstick' for sizing the human figures and outline of the spacecraft shown on the right. The hydrogen wavelength, about 8 inches, multiplied by the binary number representing '8' shown next to the woman gives her height, 64 inches. The figures represent the type of creature that created Pioneer. The man's hand is raised in a gesture of good will. Across the bottom are the planets, ranging outward from the Sun, with the spacecraft trajectory arching away from Earth, passing Mars, and swinging by Jupiter.

  16. Feedback about More Accurate versus Less Accurate Trials: Differential Effects on Self-Confidence and Activation

    ERIC Educational Resources Information Center

    Badami, Rokhsareh; VaezMousavi, Mohammad; Wulf, Gabriele; Namazizadeh, Mahdi

    2012-01-01

    One purpose of the present study was to examine whether self-confidence or anxiety would be differentially affected by feedback from more accurate rather than less accurate trials. The second purpose was to determine whether arousal variations (activation) would predict performance. On Day 1, participants performed a golf putting task under one of…

  17. A unique approach to accurately measure thickness in thick multilayers.

    PubMed

    Shi, Bing; Hiller, Jon M; Liu, Yuzi; Liu, Chian; Qian, Jun; Gades, Lisa; Wieczorek, Michael J; Marander, Albert T; Maser, Jorg; Assoufid, Lahsen

    2012-05-01

    X-ray optics called multilayer Laue lenses (MLLs) provide a promising path to focusing hard X-rays with high focusing efficiency at a resolution between 5 nm and 20 nm. MLLs consist of thousands of depth-graded thin layers. The thickness of each layer obeys the linear zone plate law. X-ray beamline tests have been performed on magnetron sputter-deposited WSi(2)/Si MLLs at the Advanced Photon Source/Center for Nanoscale Materials 26-ID nanoprobe beamline. However, it is still very challenging to accurately grow each layer at the designed thickness during deposition; errors introduced during thickness measurements of thousands of layers lead to inaccurate MLL structures. Here, a new metrology approach that can accurately measure thickness by introducing regular marks on the cross section of thousands of layers using a focused ion beam is reported. This new measurement method is compared with a previous method. More accurate results are obtained using the new measurement approach. PMID:22514179

  18. Feedback about more accurate versus less accurate trials: differential effects on self-confidence and activation.

    PubMed

    Badami, Rokhsareh; VaezMousavi, Mohammad; Wulf, Gabriele; Namazizadeh, Mahdi

    2012-06-01

    One purpose of the present study was to examine whether self-confidence or anxiety would be differentially affected byfeedback from more accurate rather than less accurate trials. The second purpose was to determine whether arousal variations (activation) would predict performance. On day 1, participants performed a golf putting task under one of two conditions: one group received feedback on the most accurate trials, whereas another group received feedback on the least accurate trials. On day 2, participants completed an anxiety questionnaire and performed a retention test. Shin conductance level, as a measure of arousal, was determined. The results indicated that feedback about more accurate trials resulted in more effective learning as well as increased self-confidence. Also, activation was a predictor of performance. PMID:22808705

  19. 9. SITE MAP HIGHLIGHTING SIGNIFICANT BUILDINGS AND SHOWING LOCATION LOCATION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. SITE MAP HIGHLIGHTING SIGNIFICANT BUILDINGS AND SHOWING LOCATION LOCATION OF OUTPATIENT CLINIC ADDITION - U.S. Veterans Administration Medical Center, 600 South Seventieth Street, Lincoln, Lancaster County, NE

  20. New model accurately predicts reformate composition

    SciTech Connect

    Ancheyta-Juarez, J.; Aguilar-Rodriguez, E. )

    1994-01-31

    Although naphtha reforming is a well-known process, the evolution of catalyst formulation, as well as new trends in gasoline specifications, have led to rapid evolution of the process, including: reactor design, regeneration mode, and operating conditions. Mathematical modeling of the reforming process is an increasingly important tool. It is fundamental to the proper design of new reactors and revamp of existing ones. Modeling can be used to optimize operating conditions, analyze the effects of process variables, and enhance unit performance. Instituto Mexicano del Petroleo has developed a model of the catalytic reforming process that accurately predicts reformate composition at the higher-severity conditions at which new reformers are being designed. The new AA model is more accurate than previous proposals because it takes into account the effects of temperature and pressure on the rate constants of each chemical reaction.